CRE 702

History

ANNOTATION Law reviews. For article, ‘‘Selecting an Ex- pert Witness’’, see 12 Colo. Law. 1464 (1983). For review, ‘‘Admissibility of Thermography: Objective Evidence or a Mystical Procedure’’, see 65 Den. U. L. Rev. 295 (1988). For article, ‘‘Hearsay as a Basis for Opinion Testimony’’, see 17 Colo. Law. 2337 (1988). For article, ‘‘DNA: The Eyewitness of the Future’’, see 18 Colo. Law. 1333 (1989). For article, ‘‘Rule 702: Admissibility of Expert Testimony Regarding Eyewitness Identification’’, see 21 Colo. Law. 927 (1992). For article, ‘‘Introduction of Scien- tific Evidence in Criminal Cases’’, see 22 Colo. Law. 273 (1993). For article, ‘‘Opinion Testi- mony’’, see 22 Colo. Law. 1185 (1993). For article, ‘‘The Misuse and Abuse of Psychologi- cal Experts in Court’’, see 23 Colo. Law. 2757 (1994). For article, ‘‘Evaluating Recovered Memories of Trauma as Evidence’’, see 25 Colo. Law. 1 (Jan. 1996). For article, ‘‘Rule 702: Admissibility of Expert Testimony’’, see 30 Colo. Law. 55 (Nov. 2001). For article, ‘‘Limits on Attorney-Expert Opinions in Jury Trials Under C.R.E. 403, 702, and 704’’, see 31 Colo. Law. 53 (Mar. 2002). For article, ‘‘Tips for Working With Evidence in Domestic Rela- tions Cases’’, see 31 Colo. Law. 87 (June 2002). For article, ‘‘Polygraph Examinations: Admissi- bility and Privilege Issues’’, see 31 Colo. Law. 69 (Nov. 2002). For article, ‘‘Challenging the Unreliable Damages Expert—Part I’’, see 32 Colo. Law. 119 (Oct. 2003). For article, ‘‘Chal- lenging the Unreliable Damages Expert—Part II’’, see 32 Colo. Law. 103 (Nov. 2003). For article, ‘‘Colorado’s Certificate of Review Stat- ute: Considerations in Professional Negligence Cases’’, see 33 Colo. Law. 11 (Feb. 2004). For article, ‘‘The Admissibility of Expert ‘Profile Evidence’’’, see 33 Colo. Law. 53 (Mar. 2004). For article, ‘‘Rules 701 and 702: Boundary Be- tween Lay and Expert Opinion Testimony’’, see 34 Colo. Law. 53 (July 2005). For article, ‘‘Us- ing Experts to Aid Jurors in Assessing Child Witness Credibility’’, see 35 Colo. Law. 65 (Aug. 2006). For article, ‘‘Lay V ersus Expert Testimony: Does V enalonzo v. People Clarify the Law?’’, see 46 Colo. Law. 46 (Aug.-Sept. 2017). For article ‘‘Horizontal Gaze Nystagmus Test Evidence in Colorado-The Framework un- der Campbell v. People’’, see 49 Colo. Law. 23 (June 2020). For article, ‘‘What’s Y our Plan? Examining Mental Health Experts in Family Law’’, see 52 Colo. Law. 34 (Jan.-Feb. 2023). This rule governs a trial court’s determi- nation regarding the admissibility of expert testimony. When proposed expert testimony in- volves experience-based specialized knowl- edge, the court must consider whether the testi- mony will be helpful to the jury and whether the witness is qualified to render an expert opin- ion on the subject in question. Meier v. McCoy, 119 P.3d 519 (Colo. App. 2004). In determining whether testimony is lay testimony or expert testimony, the trial court must look to the basis for the opinion. If the witness provides testimony that could be ex- pected to be based on an ordinary person’s experiences or knowledge, then the witness is offering lay testimony. If, on the other hand, the witness provides testimony that could not be offered without specialized experiences, knowl- edge, or training, then the witness is offering expert testimony. V enalonzo v. People, 2017 CO 9, 388 P.3d 868; Campbell v. People, 2019 CO 66, 443 P.3d 72. Determination of expert within court’s dis- cretion. The trial court has wide discretion in determining whether the requirements to qualify a witness as an expert are met. Connell v. Sun Exploration & Prod. Co., 655 P.2d 426 (Colo. App. 1982). Matter of the qualification of expert witness is discretionary with the trial court. White v. People, 175 Colo. 119, 486 P.2d 4 (1971); People v. Tidwell, 706 P.2d 438 (Colo. App. 1985); People v. Koon, 724 P.2d 1367 (Colo. App. 1986); People v. Williams, 790 P.2d 796 (Colo. 1990). The court should consider the expert’s expe- rience of the time of trial, not on the date of the alleged malpractice. Durkee v. Oliver, 714 P.2d 1330 (Colo. App. 1986); People v. Braley, 879 P.2d 410 (Colo. App. 1993). The trial court determines the qualification of witnesses and has discretion to admit expert witness testimony. Eggert v. Mosler Safe Co., 730 P.2d 895 (Colo. App. 1986). The qualification of an expert is a matter within the sound discretion of the trial judge. People v. Chavez, 182 Colo. 216, 511 P.2d 883 (1973); People v. Lomanaco, 802 P.2d 1143 (Colo. App. 1990). The qualification of expert witness to compe- tently testify on a matter of opinion is one of judicial discretion. People v. DeLuna, 183 Colo. 163, 515 P.2d 459 (1973). The qualification of an expert witness to tes- tify is within the trial court’s discretion and will not be disturbed absent an abuse of that discre- tion. Meier v. McCoy, 119 P.3d 519 (Colo. App. 2004). The competency of an expert is for the trial court to determine. People v. Anderson, 184 Colo. 32, 518 P.2d 828 (1974). Whether opinion testimony is within a wit- ness’s expertise generally is a matter addressed to the sound discretion of the court. People v. Gomez, 632 P.2d 586 (Colo. 1981), cert. de- nied, 455 U.S. 943 (1982). Trial court has broad discretion to deter- mine the admissibility of expert testimony pur- suant to this section. People v. Fasy, 820 P.2d 1314 (Colo. 1992). Generalized expert testimony fits a case if it has a sufficient logical connection to the factual issues to be helpful to the jury while still clearing the ever-present C.R.E. 403 ad- missibility bar. In evaluating the fit of general- ized expert testimony, a trial court must be mindful of the purposes for which such testi- mony is offered, that is, the reasons why the proponent of the evidence has asked the expert to educate the jury about certain concepts or principles. The fit need not be perfect, but attor- neys and trial courts should do their best to avoid introducing generalized expert testimony that has no logical connection to the facts of the case. People v. Cooper, 2021 CO 69, 496 P.3d 430; People v. Coons, 2021 CO 70, 495 P.3d 961. Generalized domestic violence expert testi- mony sufficiently fit the case facts to satisfy the admissibility requirements of this rule and CRE 403. People v. Johnson, 2022 COA 118, 523 P.3d 992. Trial court has discretion in determining the qualifications of an expert and the admissi- bility of expert evidence, and the court’s ruling will not be disturbed absent an abuse of discre- tion. Baird v. Power Rental Equip., Inc., 191 Colo. 319, 552 P.2d 494 (1976); Klein v. State Farm Mut. Auto. Ins. Co., 948 P.2d 43 (Colo. App. 1997). Abuse of discretion standard governs ap- pellate review of a trial court’s admission of expert testimony, and a trial court abuses its discretion when its decision is manifestly arbi- trary, unreasonable, or unfair. People v. Baker, 2021 CO 29, 485 P.3d 1100. Trial judge did not assume the role of ad- vocate by asking questions of a potential ex- pert witness. The court’s questions served to aid the court in determining whether the expert testimony was admissible. The nature of the questions reflect that the court was not advocat- ing a position but rather was seeking to satisfy itself—in its gatekeeper role—that the proffered scientific evidence was reliable. After the court questioned the proposed expert, the court in- vited the prosecutor and defense counsel to ask additional questions. Both sides accepted the invitation and further questioned the witness. Based on the record, the court’s questions were not of such a nature as to transform the court from neutral gatekeeper to advocate for the prosecution. People v. Medrano-Bustamante, 2013 COA 139, 412 P.3d 581, aff’d in part and rev’d in part on other grounds sub nom. Reyna- Abarca v. People, 2017 CO 15, 390 P.3d 816. Court did not abuse its discretion in deter- mining that expert witness’s opinions were based on reasonably reliable scientific prin- ciples and that the witness was qualified to render them. People v. Medrano-Bustamante, 2013 COA 139, 412 P.3d 581, aff’d in part and rev’d in part on other grounds sub nom. Reyna- Abarca v. People, 2017 CO 15, 390 P.3d 816. Court did not abuse its discretion in deny- ing defendant’s motion for a pretrial hearing on the admissibility of GPS data. GPS tech- nology is prevalent in modern society and widely regarded as reliable. People v. Camp- bell, 2018 COA 5, 425 P.3d 1163. Court’s decision not disturbed absent abuse. A court’s decision to allow a witness to testify as an expert will not be disturbed without a clear showing of an abuse of discretion. White v. People, 175 Colo. 119, 486 P.2d 4 (1971); People v. Hankin, 179 Colo. 70, 498 P.2d 1116 (1972); McCune v. People, 179 Colo. 262, 499 P.2d 1184 (1972); People v. Drumright, 181 Colo. 137, 507 P.2d 1097 (1973); People v. Anderson, 184 Colo. 32, 518 P.2d 828 (1974); Bd. of Comm’rs v. Fixed Base Operators, 939 P.2d 464 (Colo. App. 1997); People v. Bornman, 953 P.2d 952 (Colo. App. 1997). The sufficiency of foundation evidence to es- tablish qualifications and knowledge of a wit- ness to entitle him to express an opinion is a question for the trial court’s determination, and in the absence of a showing of abuse of discre- tion this determination will not be overturned. People v. Jiminez, 187 Colo. 97, 528 P.2d 913 (1974). The discretion of the trial judge over the scope of expert testimony will not be disturbed on review absent a clear showing of abuse. People v. Davis, 187 Colo. 16, 528 P.2d 251 (1974); People v. Jensen, 747 P.2d 1247 (Colo. 1987). The determination of whether a witness is qualified to render an expert opinion is commit- ted to the discretion of the trial court, and will not be disturbed on review unless that discre- tion is abused. People v. District Court, 647 P.2d 1206 (Colo. 1982). The trial court has discretion to rule upon the qualifications of expert witnesses and unless that discretion is abused its decision will not be disturbed on appeal. Stone v. Caroselli, 653 P.2d 754 (Colo. App. 1982). Trial court not required to make specific finding that witness is qualified as an expert. People v. Lomanaco, 802 P.2d 1143 (Colo. App. 1990). Disqualification of experts based on a con- flict of interest is governed by a two-part test. First, whether it was objectively reasonable for the party to conclude that a confidential rela- tionship existed with an expert consultant. Sec- ond, whether any confidential or privileged in- formation was disclosed by that party to the expert consultant. In re Page, 70 P.3d 579 (Colo. App. 2003). A confidential relationship may arise if: (1) One party has taken steps to induce another to believe that it can safely rely on the first party’s judgment or advice; (2) one party has gained the confidence of the other and purports to act or advise with the other’s interest in mind; or (3) the parties’ relationship is such that one is induced to relax the care and vigilance that ordinarily would be exercised in dealing with a stranger. In re Page, 70 P.3d 579 (Colo. App. 2003). Rule does not require previous qualifica- tion as an expert or that the proposed expert belong to any particular organization. White v. People, 175 Colo. 119, 486 P.2d 4 (1971); People v. Bornman, 953 P.2d 952 (Colo. App. 1997). Trial court inappropriately admitted lay testimony of investigating police officer as to experimentation with respect to and recon- struction of an incident without qualifying the officer as an expert witness. The officer’s testimony involved more than common experi- ence and required practical knowledge of a sci- entific, technical, or specialized nature. Admis- sion of the testimony constitutes harmless error, however, and does not require reversal. People v. Stewart, 55 P.3d 107 (Colo. 2002). Trial court erred when it allowed police officer to testify as a lay witness that he could detect the smell of metabolized alcohol and draw other conclusions based on metabolized alcohol. The portion of the officer’s testimony about metabolized alcohol was expert testimony because the opinion, as acknowledged by the officer, was based on years of experience and extensive training as a police officer. The error was not harmless because the improperly admit- ted expert testimony was the only evidence that specifically refuted defendant’s testimony. People v. Kubuugu, 2019 CO 9, 433 P.3d 1214. Trial court abused its discretion by allow- ing detective to testify as a lay witness re- garding blood spatter and blood transfer. De- tective’s testimony had the hallmarks of expert testimony, but detective had not been qualified as an expert. Detective testified about his exten- sive experience investigating cases involving blood; detective used and defined technical terms; detective testified not based on his per- sonal knowledge or investigation of the case; and the prosecutor advised the court that detec- tive was testifying as to his training and expe- rience. People v. Ramos, 2012 COA 191, 396 P.3d 21, aff’d, 2017 CO 6, 388 P.3d 888. Though expert testimony on blood pat- terns and tool markings was improperly ad- mitted, the error was harmless because the testimony did not relate to a material disputed issue, therefore any error in admitting this tes- timony could not have affected the outcome of the trial. People v. Bobian, 2019 COA 183, 461 P.3d 643. Court erred in admitting as lay testimony detective’s computer-related testimony that was based on specialized knowledge. While the detective did not claim to have specialized training in the software or expertise in forensic computer analysis, the testimony went beyond that of the average layperson, including at least some technical knowledge of the software pro- gram developed for law enforcement. People v. Froehler, 2015 COA 102, 373 P.3d 672. Court erred by allowing evidence that traced the physical address of an email sender from an internet protocol address as lay testimony. People v. Garrison, 2017 COA 107, 411 P.3d 270. Trial court improperly admitted expert testimony of police officers concerning meth- amphetamine amounts, production chemi- cals, and manufacture under the guise of lay testimony. The testimony required specialized knowledge and training and, thus, was subject to the expert witness requirements of this rule. People v. V eren, 140 P.3d 131 (Colo. App. 2005). Trial courts possess broad discretion to al- low or prohibit testimony by expert witnesses in criminal cases and an exercise of that discre- tion will not be overturned absent a showing of manifest error. People v. Lanari, 926 P.2d 116 (Colo. App. 1996). Trial court properly concluded that a wit- ness was not qualified to give expert testi- mony on the use of force by law enforcement officers effecting an arrest when the witness had never (1) been employed in a law enforcement field, (2) participated professionally in a deter- mination of what force a police officer may use in making an arrest, (3) arrested anyone, (4) completed a police officer training course, or (5) been retained by a police department to teach use of force. Meier v. McCoy, 119 P.3d 519 (Colo. App. 2004). This rule requires a two-tiered analysis for determining the reliability and validity of the underlying substance of an expert’s opinion and a trial court must balance the reliability of the scientific principles upon which the testimony rests and the likelihood that the introduction of the evidence may overwhelm or mislead the jury. Colwell v. Mentzer Inv., Inc., 973 P.2d 631 (Colo. App. 1998); Schultz v. Wells, 13 P.3d 846 (Colo. App. 2000). In exercising its discretion under this rule, the court should consider numerous factors, in- cluding the nature and extent of evidence in the case, the expertise of the proposed witness, the sufficiency and extent of the foundational evi- dence upon which the expert witness’ ultimate opinion is to be based, and the scope and con- tent of the opinion itself. People v. Lanari, 926 P.2d 116 (Colo. App. 1996); People v. Lesslie, 939 P.2d 443 (Colo. App. 1996); People v. Mas- ters, 33 P.3d 1191 (Colo. App. 2001), aff’d, 59 P.3d 979 (Colo. 2002). Lanari factors applied and admission of proffered expert testimony properly denied in People v. Miller, 981 P.2d 654 (Colo. App. 1998). This rule provides a more lenient standard for the admission of opinion evidence than does the test originally developed in Frye v. United States. The rule allows the admission of scientific evidence if such evidence will assist the jury in understanding the evidence or deter- mining a fact at issue. DNA identification testi- mony in sexual assault case admissible under the rule and under Frye. People v. Fishback, 829 P.2d 489 (Colo. App. 1991), aff’d, 851 P.2d 884 (Colo. 1993). This rule represents the appropriate stan- dard for determining the admissibility of sci- entific evidence, rather than the test devel- oped in Frye v. United States. Under the standard established in this rule, the trial should focus on the reliability and relevance of the scientific evidence and determine the reliability of the scientific principles, the qualifications of the witness, and the usefulness of the testimony to the jury. In determining the reliability and relevance of the evidence, the court should ap- ply a broad inquiry and consider the totality of the circumstances in each specific case, consid- ering a wide range of factors. Because the ap- plicable standard is so liberal, the court should also apply its discretionary authority under C.R.E. 403 to ensure the probative value of the evidence is not substantially outweighed by un- fair prejudice. People v. Shreck, 22 P.3d 68 (Colo. 2001); Masters v. People, 59 P.3d 979 (Colo. 2002); People v. Rector, 248 P.3d 1196 (Colo. 2011). Process of elimination and use of patient’s medical history to rule out alternative expla- nations for injuries are reliable scientific methods. Eliminating the presence of any ill- ness or disease and finding an absence of any accidental trauma to explain a patient’s injuries satisfy the reliability requirement of Shreck. People v. Friend, 2014 COA 123M, 431 P.3d 614, aff’d in part and rev’d in part on other grounds, 2018 CO 90, 429 P.3d 1191. Trial court has discretion to decide whether to conduct an evidentiary hearing when a party requests a Shreck analysis. A court is not required to conduct an evidentiary hearing under Shreck provided it has before it sufficient information to make specific findings under C.R.E. 403 and this rule about the reli- ability of the scientific principles involved, the expert’s qualification to testify to such matters, the helpfulness to the jury, and potential preju- dice. People v. Rector, 248 P.3d 1196 (Colo. 2011). A party raising a challenge under Shreck to the admissibility of expert testimony must sufficiently identify the testimony or witness being challenged. People v. Rector, 248 P.3d 1196 (Colo. 2011). ‘‘Reasonable medical probability’’ stan- dard should no longer be used. This rule al- lows the admission of scientific expert testi- mony when: (1) The scientific principles at issue are reasonably reliable; (2) the witness is qualified to opine on such principles; (3) the testimony is useful to the jury; and (4) the probative value of the evidence outweighs any potential prejudice. An inquiry into whether the expert expresses his or her opinion to the re- quired degree of medical probability is not ap- propriate. Estate of Ford v. Eicher, 250 P.3d 262 (Colo. 2011). The reliability analysis hinges on whether the scientific principles the expert employed are grounded in the methods and procedures of sci- ence. Estate of Ford v. Eicher, 250 P.3d 262 (Colo. 2011). ‘‘Sooner is better’’ theory regarding treat- ment for nerve damage amounts to a common- sense and universal axiom, but it is not a theory of causation. Where experts agreed that a delay in the authorization of surgery for a herniated disc was not optimal but could not opine as to how much, if at all, the delay contributed to the plaintiff’s permanent impairment, the court did not abuse its discretion in disallowing the ex- perts’ testimony. Lorenzen v. Pinnacol Assur- ance, 2019 COA 54, 457 P.3d 100. Gatekeeping function to rule out ‘‘junk science’’ only allows court to determine whether an alternative theory is reasonably reliable. The court abuses its discretion when it determines which of two competing medical theories of causation is the more plausible and prevents the expert from offering the other. Es- tate of Ford v. Eicher, 220 P.3d 939 (Colo. App. 2008), aff’d, 250 P.3d 262 (Colo. 2011). It is not for a trial court to determine whether an expert opinion is unimpeachable. To be ad- missible, expert opinion need only be reason- ably reliable based on the totality of the circum- stances. Trujillo v. V ail Clinic, 2020 COA 126, 480 P.3d 721. The fact that there is no ethical way to test an alternative medical theory does not preclude the admissibility of testimony but goes to the weight that the jury may assign to it. Estate of Ford v. Eicher, 220 P.3d 939 (Colo. App. 2008), aff’d, 250 P.3d 262 (Colo. 2011). In determining that expert’s testimony is unreliable and, therefore, should not be ad- mitted under this rule, it is not enough for a court to conclude that the testimony is ‘‘speculative’’. Instead, the court must consider whether the scientific principles underlying the testimony are reasonably reliable and whether the expert is qualified to opine on such matters. People v. Ramirez, 155 P.3d 371 (Colo. 2007). Because the trial court made no specific finding that the theory of ‘‘overkill’’ testified to by the witness was reliable, nor was the reliability of that theory either supported by the evidence in the record or accepted in Colorado, its admission was an abuse of dis- cretion. However, because there was over- whelming evidence ofdefendant’s guilt apart from the expert testimony, the error was harm- less. Ruibal v. People, 2018 CO 93, 432 P.3d 590. Statement of opinion in terms indicating a lack of certainty, such as ‘‘a possible mecha- nism’’ or ‘‘a reasonable supposition’’, do not by themselves render the opinion speculative. Estate of Ford v. Eicher, 220 P.3d 939 (Colo. App. 2008), aff’d, 250 P.3d 262 (Colo. 2011). Trial court did not commit manifest error when it determined that forensic psychologists’ testimony related to motivation and behavior of individuals committing sexual homicides, a rec- ognized subspecialty of forensic psychology, was reasonably reliable, that it was helpful to the jury, and that under C.R.E. 403 the proba- tive value of the testimony was substantially outweighed by the danger of unfair prejudice, confusion of the issues, or misleading the jury, or by considerations of undue delay, waste of time, or needless presentation of the evidence. Masters v. People, 59 P.3d 979 (Colo. 2002). A trial court has the discretion to deter- mine the admissibility of expert evidence and the trial court committed harmless error by re- fusing to permit an expert witness to testify on behalf of the plaintiff. Simon v. Truck Ins. Exch., 757 P.2d 1123 (Colo. App. 1988). Admissibility of expert evidence must be evaluated in light of its offered purpose on review for potential abuse of discretion, and prosecution’s proffered reason for admitting testimony to show the basis of the expert’s opinion that a subdural hematoma is only caused by massive, violent force was an undis- puted fact that helped the jury understand the facts of the case, and therefore was not an abuse of discretion. People v. Martinez, 74 P.3d 316 (Colo. 2003). But trial court’s admission of evidence of accident scenarios without a showing of a link between shaken-impact syndrome and the accident scenarios was error, as C.R.E. 702’s helpfulness standard requires a valid scientific connection, enunciated to the jury. People v. Martinez, 74 P.3d 316 (Colo. 2003). It was reversible error for the court to fail to apply the helpfulness standard of this rule in determining the admissibility of testimony on the reliability of eyewitness identification. Campbell v. People, 814 P.2d 1 (Colo. 1991). When expert testimony unnecessary. Where the trial court is sitting as a finder of fact and is capable of drawing its own inferences from the facts in the record, it need not admit expert testimony on a matter that it is capable of resolving without such testimony. Tri-State Generation & Transmission Co. v. City of Thornton, 647 P.2d 670 (Colo. 1982). Trial court did not abuse its discretion in admitting expert testimony where defendant did not present any evidence rebutting the reli- ability or general acceptance of the evidence. Stoczynski v. Livermore, 782 P.2d 834 (Colo. App. 1989). The basis for admissibility under this rule is not that the witness possesses skill in a particular field but that the witness can offer assistance on a matter not within the knowledge or common experience of people of ordinary intelligence. Scognamillo v. Olsen, 795 P.2d 1357 (Colo. App. 1990); Hines v. D. & R.G.W. R. Co., 829 P.2d 419 (Colo. App. 1991). The fact that a witness gained specialized knowledge while working under the supervi- sion of others does not render the witness unqualified. Town of Red Cliff v. Reider, 851 P.2d 282 (Colo. App. 1993). Expert testimony by an architect not li- censed in the state may be properly admitted if the trial court determines whether the indi- vidual’s education, training, experience, and knowledge in the field of architecture estab- lishes that he has special knowledge concerning the architectural standards, including statewide standards applicable to Colorado practitioners, and whether the testimony would aid the court. Corcoran v. Sanner, 854 P.2d 1376 (Colo. App. 1993). Competence to testify as to medical stan- dards. Generally, practitioners of one school of medicine are not competent to testify as experts relative to standards of care required of practi- tioners of another school. Greene v. Thomas, 662 P.2d 491 (Colo. App. 1982). However, a physician from one specialty may testify concerning the standard of care required of a physician with a different specialty, pro- vided that the expert witness has acquired, through experience or study, more than just a casual familiarity with the standards of care of the defendant’s specialty. Greene v. Thomas, 662 P.2d 491 (Colo. App. 1982); Connelly v. Kortz, 689 P.2d 728 (Colo. App. 1984). Where the witness and the defendant are both doctors of podiatric medicine, the testimony is admissible regardless of the difference of the practices. Durkee v. Oliver, 714 P.2d 1330 (Colo. App. 1986). A physician may be qualified as an ‘‘expert in medicine’’ rather than a specialty so long as his or her knowledge, skill, experience, train- ing, or education supports the qualification and he or she is capable of providing specialized knowledge that will assist the decision-maker in determining the issues. People ex rel. Strodtman, 293 P.3d 123 (Colo. App. 2011); Gonzales v. Windlan, 2014 COA 176, 411 P.3d 878. The test developed in Frye v. United States is applicable to novel scientific devices or pro- cesses involving the evaluation of physical evi- dence. The test contained in this rule is appli- cable if the evidence is of a general nature and the expert’s testimony does not concern this particular victim. Fishback v. People, 851 P.2d 884 (Colo. 1993) (disapproved in People v. Shreck, 22 P.3d 68 (Colo. 2001)). The test developed in Frye v. United States is applicable to the admission of novel scientific evidence. Tran v. Hilburn, 948 P.2d 52 (Colo. App. 1997), overruled by implication in People v. Shreck, 22 P.3d 68 (Colo. 2001). Frye test has not been abandoned in Colo- rado as an exclusive test of admissibility of certain expert testimony, but its application re- mains very narrow. Schultz v. Wells, 13 P.3d 846 (Colo. App. 2000). Frye test may be used only if proffered scientific evidence is based on novel scientific devices and processes involving the evaluation of physical evidence. People v. Perryman, 859 P.2d 263 (Colo. App. 1993); Schultz v. Wells, 13 P.3d 846 (Colo. App. 2000). The test established in Frye v. United States requires a showing of (1) general ac- ceptance in the relevant scientific community of the underlying theory or principle, and (2) gen- eral acceptance in the relevant scientific com- munity of the techniques used to apply that theory or principle. Fishback v. People, 851 P.2d 884 (Colo. 1993); Tran v. Hilburn, 948 P.2d 52 (Colo. App. 1997); Schultz v. Wells, 13 P.3d 846 (Colo. App. 2000). In evaluating novel scientific evidence un- der the Frye test, a court must identify the scientific theory, techniques used, and relevant scientific community at issue and then consider the evidence presented at trial, scientific litera- ture on the state of the science in question, and rulings from other jurisdictions employing the same admissibility questions. Tran v. Hilburn, 948 P.2d 52 (Colo. App. 1997). Test for admissibility of expert testimony that does not deal with scientific devices or processes is whether the testimony will assist the trier of fact to understand the evidence or fact in issue. Colwell v. Mentzer Invs., Inc., 973 P.2d 631 (Colo. App. 1998). To determine the admissibility of this type of testimony, the court must hold an in limine proceeding to balance the reliability of the sci- entific principles upon which the testimony rests with the likelihood that the testimony may overwhelm or mislead the jury. Colwell v. Mentzer Invs., Inc., 973 P.2d 631 (Colo. App. 1998). Applying this test, the court did not abuse its discretion in admitting testimony concerning the effect of stress on causing multiple sclerosis to become symptomatic. Colwell v. Mentzer Invs., Inc., 973 P.2d 631 (Colo. App. 1998). Neither of the tests established in Frye v. United States or Daubert v. Merrell Dow Phar- maceuticals is applicable to dog-tracking evi- dence because it does not depend upon any scientific device, method, or process. People v. Brooks, 950 P.2d 649 (Colo. App. 1997), aff’d, 975 P.2d 1105 (Colo. 1999). Instead, such evidence concerns a subject of common knowledge: Some dogs can track. While specialized knowledge is involved, the reliability of a particular track is typically dem- onstrated by evidence that is easily understood by a jury such as the handler’s experience, knowledge, and training. People v. Brooks, 950 P.2d 649 (Colo. App. 1997), aff’d, 975 P.2d 1105 (Colo. 1999). Elements of a proper foundation for dog tracking evidence listed in Brooks v. People, 975 P.2d 1105 (Colo. 1999). Harmless error to admit dog tracking evi- dence, despite improper foundation, where dog handler later testified she and the dog had worked together for five years and performed numerous narcotics sniffs, and that the dog had never alerted officers about money determined to be clean. People v. Martinez, 51 P.3d 1029 (Colo. App. 2001), aff’d in part and rev’d in part on other grounds, 69 P.3d 1029 (Colo. 2003). Frye test does not apply to shoe print iden- tification. The expert’s comparative process in- volves no ‘‘manipulation’’ of evidence, and an understanding of the techniques used is readily accessible to the jury. People v. Perryman, 859 P.2d 263 (Colo. App. 1993); People v. Fears, 962 P.2d 272 (Colo. App. 1997). Frye test should not have been used to exclude evidence related to the results of auto- mobile collision experiments with human vol- unteers as the tests did not involve a novel scientific process or device applied to the ma- nipulation of physical evidence, but exclusion was nonetheless proper as the trial court did not rely exclusively on the Frye test but also ap- plied C.R.E. 402 and this rule. Schultz v. Wells, 13 P.3d 846 (Colo. App. 2000). Concerns which may arise in the imple- mentation of otherwise generally accepted techniques go to the weight to be accorded to scientific or technical evidence and not to the admissibility of such evidence. Fishback v. People, 851 P.2d 884 (Colo. 1993). Evidence derived from multiplex DNA testing systems was admissible under this rule based on the supreme court findings that multiplex systems are generally reliable, ques- tions as to the reliability of a specific type of multiplex system go to the weight of the evi- dence, and the specific multiplex systems used in this case had been deemed reliable by other courts. Further, the court found that the proba- tive value of the evidence was not substantially outweighed by the danger of unfair prejudice, confusion, delay, waste of time, or needless presentation of cumulative evidence under C.R.E. 403. People v. Shreck, 22 P.3d 68 (Colo. 2001); People v. Lehmkuhl, 117 P.3d 98 (Colo. App. 2004). Inconclusive and no conclusion DNA evi- dence is not relevant direct evidence. People v. Marks, 2015 COA 173, 374 P.3d 518. Quantitative electroencephalogram (QEEG), which is a computer enhanced elec- troencephalogram that compares a patient’s brain activity with the activity of normally functioning brains, is not generally accepted in the community of clinicians who treat brain injured patients and QEEG evidence is thus not admissible. Tran v. Hilburn, 948 P.2d 52 (Colo. App. 1997). But videofluoroscopy (VF), which is a vid- eotaped x-ray motion picture of a patient’s bones and soft tissue structures in motion, is generally accepted by the relevant community of chiropractic professionals and VF evidence is thus admissible. Tran v. Hilburn, 948 P.2d 52 (Colo. App. 1997). The water court properly excluded results derived from surface and ground water mod- els because of a lack of reliability caused by a variety of technical failures by the expert wit- nesses. In re Water Rights of Park County Sportsmen’s Ranch, 105 P.3d 595 (Colo. 2005). Exclusion of testimony held abuse of dis- cretion where oral surgeon had testified as to standard of care for general dentist after the trial court had accepted the witness as an expert in both fields, neither the defendant nor the court had objected to the surgeon’s qualification as an expert witness at the time of his testimony, and surgeon had testified that the standard of care for extraction of tooth would be the same for both practitioners. Surgeon’s statement, in re- sponse to questioning of court, that he could not testify to the overall standard of care for general dentists goes to the weight to be accorded to testimony rather than to its admissibility. San- chez v. Lauffenburger, 784 P.2d 855 (Colo. App. 1989). Attorneys may testify as experts with re- spect to insurance industry standards. Klein v. State Farm Mut. Auto. Ins. Co., 948 P.2d 43 (Colo. App. 1997). Certified public accountant (CPA) quali- fied as expert in accounting. A trial court has discretion in determining the qualifications of an expert and the admissibility of expert evi- dence. That discretion is properly exercised where a certified public accountant is properly qualified as an expert in accounting and he testifies only regarding his professional opin- ions as a CPA which have to be made by him in the performance of his duties. Andrikopoulos v. Broadmoor Mgt. Co., 670 P.2d 435 (Colo. App. 1983). Police officers employed in crime lab may testify as experts. A trial court does not abuse its discretion in allowing police officers em- ployed in the crime laboratory to testify as ex- perts when the technicians have qualifications as experts based on technical training and pre- trial experience, and the jury is adequately in- structed on the weight to be given expert testi- mony and opinion evidence. People v. Hankin, 179 Colo. 70, 498 P.2d 1116 (1972). There is no requirement that a forensic chemistry expert follow a ‘‘written analytical method’’ before his or her expert testimony may be admitted. Based on the totality of the circumstances, the trial court did not abuse its discretion in admitting the expert testimony without a ‘‘written analytical method’’. People v. Laurent, 194 P.3d 1053 (Colo. App. 2008). Testimony concerning Mexican culture did not constitute specialized knowledge that would assist the trier of fact, and exclusion of proffered expert testimony did not deprive de- fendant of his constitutional right to present a defense. People v. Salcedo, 985 P.2d 7 (Colo. App. 1998), rev’d on other grounds, 999 P.2d 833 (Colo. 2000). Fact that witness not college graduate does not preclude his testifying as expert. The fact that a police officer is not a college graduate does not preclude his testifying as an expert on the basis of other technical training and pretrial experience. White v. People, 175 Colo. 119, 486 P.2d 4 (1971). Error not found in allowing handwriting expert to testify. People v. Drumright, 181 Colo. 137, 507 P.2d 1097 (1973). Court did not abuse its discretion in refus- ing to qualify defendant’s witness as an ex- pert. The witness claimed that his expert knowledge was self-taught, but he did not ex- plain how he learned about medical marijuana grows. Although expertise can be based solely on experience, the court had no basis to deter- mine whether the testimony was reliable with- out additional information about the genesis of his knowledge and skills. People v. Douglas, 2015 COA 155, 412 P.3d 785. Jury is not bound by the testimony of ex- pert witnesses, which must be considered and weighed as that of other witnesses. People v. King, 181 Colo. 439, 510 P.2d 333 (1973). A medical opinion is admissible if founded on reasonable medical probability. Thirsk v. Ethicon, Inc., 687 P.2d 1315 (Colo. App. 1983). These rules, not the standard of ‘‘reason- able medical probability’’, govern the admis- sibility of expert testimony. To the extent ear- lier cases approve of this standard, they are overruled. People v. Ramirez, 155 P.3d 371 (Colo. 2007). Internist not allowed to testify regarding the practice of surgeons. Trial court did not abuse its discretion in refusing to allow internist to testify to the standards of practice of sur- geons in the Denver metropolitan area when proponent failed to demonstrate that the stan- dards of care in the two fields are in fact similar, and there was testimony that the standards of practice concerning the need for surgery fol- lowed by surgeons differ from the standards of practice followed by internists. Connelly v. Kortz, 689 P.2d 728 (Colo. App. 1984). Dispositive consideration in ruling on ad- missibility of medical witness’ expert testi- mony regarding whether the defendant, who practices in another school of medicine, has adhered to or deviated from the requisite stan- dard of care should be (1) whether the expert is, by reason of knowledge, skill, experience, training, or education, so substantially familiar with the standard or care applicable to the de- fendant’s specialty as to render the witness’ opinion testimony as well-informed as would be the opinion of an expert witness practicing the same specialty as the defendant, or (2) whether the standard of care for the condition in ques- tion is substantially identical for both special- ties. Melville v. Southward, 791 P.2d 383 (Colo. 1990). Expert’s testimony of personal practices may be admissible if an expert testified con- cerning the applicable standard of care be- cause (1) expert’s personal practices may help jurors understand why that standard of care is followed; (2) testimony regarding personal practices may either bolster or impeach the credibility of the expert; and, (3) each expert addressed the applicable standard of care. Wallbank v. Rothenberg, 74 P.3d 413 (Colo. App. 2003). Expert testimony by a physician who had never conducted an examination for a medi- cal marijuana applicant may properly be ad- mitted where the defendant provides no author- ity to show that the medical assessment and diagnosis required for a medical marijuana rec- ommendation differ from that performed by physicians for other purposes. People v. Montante, 2015 COA 40, 351 P.3d 530. Testimony of orthopedic surgeon should not have been admitted on the issue of podia- trist’s alleged negligence. The plaintiff failed to establish that the orthopedic surgeon was so substantially familiar with the standard of care for podiatric surgery as to render his opinion testimony as well-informed as that of a podia- trist and failed to establish that the standard of care for the surgery was substantially identical for both the practice of orthopedic surgery and podiatry. Melville v. Southward, 791 P.2d 383 (Colo. 1990). Neuropsychologists are not per se unquali- fied to speak on the causation of organic brain injury, but a court must satisfy the two- part approach to questions arising under this rule. Huntoon v. TCI Cablevision of Colo., 969 P.2d 681 (Colo. 1998). Trial court did not err when it permitted a physician accepted as an expert in plastic and reconstructive surgery and the care of burn patients to testify that he had discontin- ued a steroid treatment after burn victim reported gynecological symptoms where phy- sician was not offering an expert opinion on gynecological and obstetrical medicine but rather was giving the reasons for his course of treatment, which were based on the burn vic- tim’s physical response to the treatment. Simon v. Coppola, 872 P.2d 10 (Colo. App. 1993). In a trial for sexual assault on a child, the trial court did not err in admitting testimony by the child’s therapist, a social worker, about the characteristics present in sexually abused children, the presence of similar characteristics in the child, and the purpose of therapy since such testimony does not rise to the level of an improper assertion that the child was telling the truth and the testimony would assist the jury in determining a fact in issue. People v. Cordova, 854 P.2d 1337 (Colo. App. 1992). In a first-degree sexual assault trial, testi- mony of counselor consisting of general com- ments based on her observations of victim’s demeanor following alleged sexual assault was not inadmissible as amounting to a scientific diagnosis of rape trauma syndrome, as long as counselor did not use scientific terminology, discuss theory, or state an opinion as to whether she believed victim. People v. Farley, 712 P.2d 1116 (Colo. App. 1985), aff’d, 746 P.2d 956 (Colo. 1987). The trial court did not err by allowing expert testimony in sexual assault case be- cause the lay notion of what behavior follows being raped may not be consistent with the behavior that social scientists have found. This satisfies the test that expert testimony be helpful to the jury. Further, rape trauma syndrome evi- dence has repeatedly been held to be reliable. People v. Baenziger, 97 P.3d 271 (Colo. App. 2004). Denial of effective counsel. Admission of testimony of defense-retained handwriting ex- pert called by prosecution constitutes denial of effective assistance of counsel. Perez v. People, 745 P.2d 650 (Colo. 1987). Expert witness evidence not admissible. Where expert witness’ opinion evidence would not assist the trier of fact in understanding the evidence and where evidence is not of a techni- cal or complex nature, expert testimony is not admissible under this rule. People v. Snook, 729 P.2d 1026 (Colo. App. 1986), aff’d, 745 P.2d 647 (Colo. 1987). This rule was not intended to allow expert testimony on the issue of whether a witness is telling the truth. People v. Snook, 729 P.2d 1026 (Colo. App. 1986), aff’d, 745 P.2d 647 (Colo. 1987). Court properly excluded defendant’s ex- pert heat of passion testimony because the heat of passion mitigator does not apply when a person seeks out the highly provoking act in question, as defendant did here. Therefore, trial court properly excluded the testimony since it would not have been helpful to the jury. People v. V aldez, 183 P.3d 720 (Colo. App. 2008). Expert’s testimony that victim’s state- ments are consistent with the medical diag- nosis do not constitute a subjective opinion concerning the veracity of victim’s state- ments, therefore the testimony may be properly admitted. People v. Wittrein, 198 P.3d 1237 (Colo. App. 2008), rev’d on other grounds, 221 P.3d 1076 (Colo. 2009). Doctor’s testimony that she could not imagine that victim’s story was fabricated was improper since it was an opinion that victim was telling the truth. People v. Wittrein, 198 P.3d 1237 (Colo. App. 2008), aff’d, 221 P.3d 1076 (Colo. 2009). However, the error was invited by defense counsel’s questioning, so reversal is not re- quired. People v. Wittrein, 221 P.3d 1076 (Colo. 2009). Juvenile court erred by admitting child abuse pediatrician’s testimony that impermis- sibly bolstered victim’s credibility and usurped the jury’s role as fact finder. The testimony crossed the line into impermissible opinion tes- timony that the victim’s allegations were cred- ible, and that sexual abuse had occurred. People in Interest of J.R., 2021 COA 81, 495 P.3d 346. Although the error in admitting the pediatri- cian’s testimony was obvious, it was not so substantial that it cast serious doubt on the reli- ability of the verdict. People in Interest of J.R., 2021 COA 81, 495 P.3d 346. While expert opinion on whether children generally have the sophistication to lie about having experienced a sexual assault is admis- sible, neither a lay nor expert witness may give opinion testimony with respect to whether a witness is telling the truth on a specific occa- sion. Such testimony invades the province of the jury with respect to its determination of credibility. People v. Higa, 735 P.2d 203 (Colo. App. 1987). The trial court erred in allowing expert to testify that children and teenagers rarely fabricate allegations of sexual abuse and re- garding the incidence of sexual abuse. The error was ‘‘obvious’’ and ‘‘substantial’’ and re- quires reversal of conviction, whether under plain error or another standard of review. People v. Marx, 2019 COA 138, 467 P.3d 1196. Expert testimony on ‘‘rape trauma syn- drome’’ admissible on issue of victim’s delay in reporting sexual assault where testimony concerned only existence of syndrome and did not involve specific diagnosis of victim. People v. Hampton, 746 P.2d 947 (Colo. 1987). Defense may present expert testimony as to defendant’s state of mind in order to bolster a claim of self-defense in a homicide case. People v. Y oung, 825 P.2d 1004 (Colo. App. 1991). Expert testimony on posttraumatic syn- drome admissible on issue of child victim’s delay in reporting sexual assault, where testi- mony of expert did not address opinion as to truthfulness of child’s statements. People v. Fasy, 829 P.2d 1314 (Colo. 1992). Expert’s testimony was properly received to aid the jury in understanding the typicality of reactions by children who have been subjected to sexual abuse. Because the expert testified in general terms, did not focus on the truthfulness of the child’s statements, and did not make any explicit reference to the child’s truthfulness, it was proper expert testimony. People v. Morri- son, 985 P.2d 1 (Colo. App. 1999), aff’d on other grounds, 19 P.3d 668 (Colo. 2000); People v. Mintz, 165 P.3d 829 (Colo. App. 2007); People v. Short, 2018 COA 47, 425 P.3d 1208. Trial court did not abuse its discretion by finding that an expert’s explanation of possible child behaviors and reactions would be helpful to the trier of fact and was admissible. People v. Whitman, 205 P.3d 371 (Colo. App. 2007). Admissibility of expert testimony based on results of absorption inhibition testing in rape case. Since the absorption inhibition method has been recognized as based upon ac- cepted scientific principles, trial court admis- sion of such evidence based upon an offer of proof was a proper exercise of discretion. People v. Banks, 804 P.2d 203 (Colo. App. 1990). Testimony by voice-print expert is not suf- ficiently reliable to be admissible. People v. Drake, 748 P.2d 1237 (Colo. 1988). Investigating police officer determined to be expert. An investigating police officer may give expert opinion if the subject is complex, is susceptible to opinion evidence, and the witness is qualified to give an opinion. Eggert v. Mosler Safe Co., 730 P.2d 895 (Colo. App. 1986). Trial court did not err in refusing to per- mit expert testimony on the factors affecting the reliability of eyewitness identification. People v. Beaver, 725 P.2d 96 (Colo. App. 1986). Expert testimony on the reliability of eyewit- ness identification is not per se admissible. Rather, admissibility of such evidence is left to the trial court’s discretion. The trial judge must consider both this rule and C.R.E. 403 in deter- mining the admissibility of such evidence and such determination may not be reversed unless it is manifestly erroneous. Campbell v. People, 814 P.2d 1 (Colo. 1991). Trial court did not err in admitting results of a defendant’s breath-alcohol test and allow- ing expert witness to testify about alcohol’s effect on a person’s inhibitions. People v. Covington, 988 P.2d 657 (Colo. App. 1999), rev’d on other grounds, 19 P.3d 15 (Colo. 2001). The trial court has broad discretion to evaluate on a case by case basis whether expert testimony on the issue would assist the trier of fact to understand evidence or to determine facts in issue. The appellate court will not reverse the trial court’s ruling to admit or exclude such expert testimony unless the ruling is manifestly erroneous. People v. Kemp, 885 P.2d 260 (Colo. App. 1994). Admissibility of experience-based special- ized knowledge that is not dependent on a scientific explanation depends on whether the evidence is reasonably reliable informa- tion that will assist the trier of fact, which question requires the court to find that the testi- mony on the subject would be useful to the jury and that the witness is qualified to render an opinion on the subject. Brooks v. People, 975 P.2d 1105 (Colo. 1999); Salcedo v. People, 999 P.2d 833 (Colo. 2000). Trial court erred in excluding expert testi- mony on reliability of eyewitness identifica- tion where eyewitness identification of defen- dant was the only substantial element of the prosecution’s case, eyewitnesses expressed high confidence in their identification of defendant, and proffered expert testimony would have shown a poor relationship between the confi- dence of eyewitnesses, in general, and the reli- ability of such witnesses’ testimony. People v. Campbell, 847 P.2d 228 (Colo. App. 1992). Trial court erred in excluding expert testi- mony on the whether all of the damages were foreseeable. It was sufficient that the expert’s testimony permitted the jury to infer that not all of the damages were foreseeable even if the expert did not qualify how much was not fore- seeable. Core-Mark Midcontinent v. Sonitrol Corp., 2012 COA 120, 300 P.3d 963. Three-part test under equivalent federal rule applied in People v. Campbell, 847 P.2d 228 (Colo. App. 1992). Where challenged testimony addressed a collection of behaviors which are typical of children who have been sexually abused, the fact that some of these behaviors were observed as occurring in the victim serves the proper purposes of corroborating the testimony of the victim and does not make such testimony inad- missible. The testimony of the dynamics of child sexual assault could be used by the jury to understand the evidence and determine facts in issue and was properly admitted. People v. Woertman, 786 P.2d 443 (Colo. App. 1989). Expert testimony concerning drug courier profile was not properly admitted because it was not helpful to the jury since it was inher- ently subjective, of dubious reliability, and logi- cally irrelevant, and because its probative value was substantially outweighed by a risk of mis- leading the jury. Salcedo v. People, 999 P.2d 833 (Colo. 2000). Trial court abused its discretion by admit- ting (1) testimony from a police officer, the prosecution’s expert, that, based on his expe- rience and a windshield experiment he had conducted, the elliptical shape of the bullet hole was more consistent with a shot fired from shoulder height than with a shot fired at the stick shift level; and (2) evidence of the results of the windshield experiment. The officer did not describe the methodology underlying the testing of shots through a windshield, the pur- pose of that testing, the analysis conducted, or the results of that testing beyond his conclusion that shots fired at an angle produce elliptical bullet holes. And the statements did nothing to establish that he or anyone else could reliably apply his theory to interpret the shape of the bullet hole in the case. People v. Ornelas- Licano, 2020 COA 62, 490 P.3d 714. Evidence of child sexual abuse and sex offender characteristics was not improper ‘‘profile’’ evidence, but was designed to aid the jury regarding the modus operandi of sex of- fenders and was useful because jurors cannot be presumed to have knowledge of such character- istics. People v. Conyac, 2014 COA 8M, 361 P.3d 1005. Present or former employees of the insur- ance industry are not the only persons quali- fied to render expert opinions about its op- eration. Attorneys with extensive experience in workers’ compensation who have dealt exten- sively with defendant and other insurance com- panies may testify as experts regarding the stan- dard of good faith conduct of an insurer. Southerland v. Argonaut Ins. Co., 794 P.2d 1102 (Colo. App. 1990). Trial court did not abuse discretion by not accepting a convict to testify as an expert witness in parole procedures. Cardiel v. Brittian, 833 P.2d 748 (Colo. 1992). District court did not abuse discretion in denying habeas corpus petitioner proffered ex- pert witness. Although witness, a fellow inmate of the petitioner, had some training and experi- ence with habeas corpus petitions and other parole issues, trial court cannot be found to have abused its discretion in refusing to accept the witness as an expert in administrative pro- cedures concerning parole. Cardiel v. Brittian, 833 P.2d 748 (Colo. 1992). This rule contained the appropriate test to determine the admissibility of expert testi- mony when the process used by the expert involved no manipulation of physical evidence and the understanding of the expert’s tech- niques was readily accessible to the jury. The expert’s testimony compared the characteristics of defendant’s shoes with prints found near the victim’s body. People v. Perryman, 859 P.2d 263 (Colo. App. 1993). A court may rely on the testimony of a single witness in admitting scientific evidence under Frye if the witness is qualified to render an opinion as to the general acceptance of the techniques and the opposing party has the op- portunity to cross-examine the expert. People v. Perryman, 859 P.2d 263 (Colo. App. 1993). Where expert witness had 16 years’ expe- rience, was familiar with literature in the field, and had testified as an expert in numer- ous prior cases the court could rely on such expert’s testimony without additional, indepen- dent expert testimony. People v. Perryman, 859 P.2d 263 (Colo. App. 1993). Court did not abuse its discretion in deeming witness qualified to testify as an expert given witness’s extensive experience, knowledge, and training. People v. Rojas, 181 P.3d 1216 (Colo. App. 2008). Where expert’s opinion is based upon reli- able data, including unrebutted published studies and the treatment of at least 50 pa- tients with exposure to the same toxic sub- stance as that to which plaintiff was exposed, there was no error in admitting testimony re- garding causation, as it is both helpful and com- petent. Salazar v. Am. Sterlizer Co., 5 P.3d 357 (Colo. App. 2000). Court did not abuse its discretion in con- cluding that a witness who was not a real estate appraiser could offer testimony con- cerning property values. The court was satis- fied that the extent of the witness’s training and experience qualified him to express an expert opinion regarding the effect of environmental contamination on property values even though he was not a real estate appraiser. Antolovich v. Brown Group Retail, Inc., 183 P.3d 582 (Colo. App. 2007). Trial court did not abuse its discretion in allowing witness to testify as an expert in fingerprint comparison when witness com- pleted a sixteen-hour class over a month-long period only five years earlier, attended several informal training review classes since then, conducted at least seventy-three fingerprint comparisons, was previously qualified as an ex- pert in fingerprint comparison thirteen times, and has another person perform independent comparison to verify witness’s fingerprint com- parison finding. People v. Lowe, 2020 COA 116, 486 P.3d 397. Where substantial expert testimony con- cerning DNA testing supported admissibility of DNA evidence, it was within the trial court’s discretion to allow consideration of the evi- dence. People v. Lindsey, 868 P.2d 1085 (Colo. App. 1993). Trial court did not err in admitting DNA evidence where DNA expert could not defi- nitely identify victim as a contributor of the DNA. Testimony was relevant in that it showed it was more probable than not that victim con- tributed to the DNA. People v. Rojas, 181 P.3d 1216 (Colo. App. 2008). Expert testimony that there are no physi- cal findings in 90 to 95 percent of child sex assault cases was relevant to rebut defense counsel’s argument concerning the lack of physical evidence and to explain to the jury why the lack of physical findings in victim’s case did not refute the allegations. People v. Conyac, 2014 COA 8M, 361 P.3d 1005. Although an expert witness should not dic- tate the law that a jury should apply, an expert witness is permitted, in the trial court’s discretion, to refer to the facts of a case in legal terms. Thus, expert’s testimony was admissible insofar as it concerned party’s contention that insurer’s conduct constituted bad faith based on purported violations of the Unfair Claims Settlement Practices Act. Such testimony was helpful as it served to explain complex issues of insurance company claims management practices. Peiffer v. State Farm Mut. Auto. Ins., 940 P.2d 967 (Colo. App. 1996), aff’d on other grounds, 955 P.2d 1008 (Colo. 1998). Any legal conclusions tendered by witness were elicited during her cross-examination by defendant’s counsel, and thus, any error regarding witness’s testimony was injected at defendant’s behest. Such error cannot serve as grounds for reversal on appeal by defendant. Bd. of Comm’rs v. Fixed Base Operators, 939 P.2d 464 (Colo. App. 1997). No abuse of discretion for trial court to permit expert testimony regarding the steps a reasonably prudent applicant in a Torrens action would take to ascertain the names of persons who claimed an interest in the property and to rely on that testimony in reaching its conclusions on due process issues. Lobato v. Taylor, 13 P.3d 821 (Colo. App. 2000), rev’d on other grounds, 71 P.3d 938 (Colo. 2002). Expert testimony concerning reasons for victims’ recantations is admissible in cases involving domestic violence. People v. John- son, 74 P.3d 349 (Colo. App. 2002); People v. Wallin, 167 P.3d 183 (Colo. App. 2007). Trial court properly excluded expert wit- ness’s testimony as unnecessary and as im- properly usurping the court’s function be- cause: (1) The testimony was not needed to describe or interpret the crime setting; (2) the testimony was not a question for the jury; (3) the testimony would not have assisted the trier of fact; and (4) an expert testifying as to issues of law may not simply tell the jury what result to reach. People v. Lesslie, 939 P.2d 443 (Colo. App. 1996). Prosecutor’s use of expert testimony re- garding drug courier profiles as substantive evidence of defendant’s guilt was improper, and, although a reasonable jury could have con- victed on other evidence, the admissible evi- dence did not overwhelmingly establish defen- dant’s guilt, and there is a significant probability that the erroneously admitted testi- mony substantially influenced the jury’s verdict, and thus was not harmless. Salcedo v. People, 999 P.2d 833 (Colo. 2000). Court abused its discretion in admitting some lay opinions from mental health pro- viders who had not been properly noticed as experts by the prosecution. Some of the opin- ions were expert opinions improperly admitted under the guise of lay opinion testimony. The improper testimony related to symptoms of spe- cific mental illness and opinions about whether defendant suffered from mental illness. The evi- dence relied upon the witness’ specialized knowledge and training and, therefore, went beyond the bounds of lay opinion. The error in this case was harmless since there was ample evidence in addition to the improperly admitted opinions. Dunlap v. People, 173 P.3d 1054 (Colo. 2007), cert. denied, 552 U.S. 1105 (2008). Trial court abused its discretion by admit- ting the expert testimony of the deputy commis- sioner of the state division of securities that the defendant in a securities fraud case had made material misstatements and omissions when communicating with plaintiff investors. The commissioner spoke as though disputed facts were true and disputed witness statements were accurate and thereby usurped the function of the jury by effectively weighing and making cred- ibility determinations regarding the evidence and essentially telling the jury what had oc- curred. In addition, the error was not harmless. People v. Baker, 2021 CO 29, 485 P.3d 1100. Mathematical probability statements or numerical conclusions by an expert witness on ergonomics properly excluded if (1) the conclusion was without statistical support in the record and (2) such a statement or conclusion implied a non-purposeful or non-intentional state of mind by the defendant and the expert was not qualified to testify regarding the defen- dant’s psychological condition. People v. Wilkerson, 114 P.3d 874 (Colo. 2005). Allowing police officer’s testimony regard- ing the use of glass pipe and torch lighter to smoke methamphetamine not plain error. People v. Malloy, 178 P.3d 1283 (Colo. App. 2008). No plain error in allowing detective to of- fer expert testimony without qualifying him as an expert when the detective was qualified to provide the opinions, defendant’s counsel failed to object to the detective’s testimony or request a continuance after the jury heard it, and the evidence against defendant was overwhelm- ing. People v. Martinez, 2020 COA 141, 486 P.3d 412. Cranial compression ischemic encepha- lopathy testimony was reasonably reliable, helpful to a jury, and admissible under C.R.E. 403. Therefore the trial court manifestly erred by excluding it. Trujillo v. V ail Clinic, 2020 COA 126, 480 P.3d 721. Trial court improperly limited testimony of defendant’s expert witness after prosecu- tion had opened the door to this testimony and error was not harmless beyond a reasonable doubt. Golob v. People, 180 P.3d 1006 (Colo. 2008). Child forensic interviewer’s testimony that the alleged victim did not seem to be coached, although normally not admissible, was admissible because the defense opened the door to the questioning. People v. Heredia- Cobos, 2017 COA 130, 415 P.3d 860. Trial court did not abuse its discretion in requiring defendant to present his expert tes- timony in court rather than through video- conferencing. People v. Casias, 2012 COA 117, 312 P.3d 208. Videos introduced at trial were animations not simulations, so they are not subject to the scientific evidence standard of this rule. The videos were animations because: an officer sup- plied the calculations and opinions used to cre- ate the videos; the officer formed the opinions based on a review of the physical evidence and the victim’s statements; the videos were demon- strative exhibits that illustrated the officer’s opinion; and the jury knew the videos were not a re-creation of the actual event. People v. Douglas, 2016 COA 59, 411 P.3d 1026. Using historical cell site data to determine the general geographic location of a cell phone is widely accepted as reliable and does not require a Shreck hearing. The district court did not abuse its discretion by denying defendant’s request for a Shreck hearing. People v. Shanks, 2019 COA 160, 467 P.3d 1228. Applied in People in Interest of K.A.J., 635 P.2d 921 (Colo. App. 1981); People v. Ortega, 672 P.2d 215 (Colo. App. 1983); People v. Jones, 743 P.2d 44 (Colo. App. 1987); People v. Williams, 761 P.2d 258 (Colo. App. 1988); People v. Groves, 854 P.2d 1310 (Colo. App. 1992); People v. Masters, 33 P.3d 1191 (Colo. App. 2001), aff’d, 59 P.3d 979 (Colo. 2002); People v. Martinez, 51 P.3d 1029 (Colo. App. 2001), aff’d in part and rev’d in part on other grounds, 69 P.3d 1029 (Colo. 2003); Luster v. Brinkman, 205 P.3d 410 (Colo. App. 2008).