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:
(1) the opportunity and ability of the witness to see or hear or know the things testified to;
(2) the witness’s memory;
(3) the witness’s manner while testifying;
(4) the witness’s interest in the outcome of the case, if any;
(5) the witness’s bias or prejudice, if any;
(6) whether other evidence contradicted the witness’s testimony;
(7) the reasonableness of the witness’s testimony in light of all the evidence; and
(8) 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.
The weight of the evidence as to a fact does not necessarily depend on the number of witnesses who testify. What is important is how believable the witnesses were, and how much weight you think their testimony deserves.
The Committee recommends that the jurors be given some guidelines for determining credibility at the beginning of the trial so that they will know what to look for when witnesses are testifying.