N.H. R. Crim. P. 20

(a) Joinder of Offenses

(1) Related Offenses. Two or more offenses are related if they:

(A) Are alleged to have occurred during a single criminal episode; or

(B) Constitute parts of a common scheme or plan; or

(C) Are alleged to have occurred during separate criminal episodes, but nonetheless, are logically and factually connected in a manner that does not solely demonstrate that the accused has a propensity to engage in criminal conduct.

(2) Joinder of Related Offenses for Trial. If a defendant is charged with two or more related offenses, either party may move for joinder of such charges. The trial judge shall join the charges for trial unless the trial judge determines that joinder is not in the best interests of justice.

(3) Joinder of Unrelated Offenses. Upon written motion of a defendant, or with the defendant's written consent, the trial judge may join for trial two or more charges of unrelated offenses upon a showing that failure to try the charges together would constitute harassment or unduly consume the time or resources of the parties. The trial judge shall join the charges for trial unless the trial judge determines that joinder is not in the best interest of justice.

(4) Mandatory Joinder-Limitations on Separate Trials for Multiple Offenses. Except as provided in Subsection (5), a defendant shall not be subject to separate trials for multiple offenses based on the same conduct or arising from the same criminal episode, if such offenses are known to the appropriate prosecuting officer at the time of the commencement of the first trial and are within the jurisdiction of a single court.

(5) Relief from Prejudicial Joinder. If it appears that a joinder of offenses is not in the best interests of justice, the court may upon its own motion or the motion of either party order an election of separate trials or provide whatever other relief justice may require.

(b) Joinder of Defendants. If two or more defendants are charged with related offenses as defined in Rule 20(a)(1), the court may order joinder of the trials of the defendants so long as joinder does not violate the constitutional rights or otherwise unduly prejudice any of the defendants.