9th Cir. Model Jury Instr. (Criminal) 1.7

In deciding the facts in this case, you may have to decide which testimony to believe and which testimony not to believe. You may believe everything a witness says, or part of it, or none of it.

In considering the testimony of any witness, you may take into account:

First, the witness’s opportunity and ability to see or hear or know the things testified to;

Second, the witness’s memory;

Third, the witness’s manner while testifying;

Fourth, the witness’s interest in the outcome of the case, if any;

Fifth, the witness’s bias or prejudice, if any;

Sixth, whether other evidence contradicted the witness’s testimony;

Seventh, the reasonableness of the witness’s testimony in light of all the evidence; and

Eighth, any other factors that bear on believability.

Sometimes a witness may say something that is not consistent with something else he or

she said. Sometimes different witnesses will give different versions of what happened. People

often forget things or make mistakes in what they remember. Also, two people may see the same event but remember it differently. You may consider these differences, but do not decide that testimony is untrue just because it differs from other testimony.

However, if you decide that a witness has deliberately testified untruthfully about

something important, you may choose not to believe anything that witness said. On the other

hand, if you think the witness testified untruthfully about some things but told the truth about

others, you may accept the part you think is true and ignore the rest.

You must avoid bias[, conscious or unconscious,] based on a witness’s race, color, religious beliefs, national ancestry, sexual orientation, gender identity, gender, or economic circumstances in your determination of credibility.

The weight of the evidence as to a fact does not necessarily depend on the number of witnesses who testify about it. What is important is how believable the witnesses are, and how much weight you think their testimony deserves.