California Civil Jury Instructions (CACI)

107. Witnesses


A witness is a person who has knowledge related to this case. You will have to decide whether you believe each witness and how important each witness’s testimony is to the case. You may believe all, part, or none of a witness’s testimony.

In deciding whether to believe a witness’s testimony, you may consider, among other factors, the following:

(a) How well did the witness see, hear, or otherwise sense what he or she described in court?

(b) How well did the witness remember and describe what happened?

(c) How did the witness look, act, and speak while testifying?

(d) Did the witness have any reason to say something that was not true? For example, did the witness show any bias or prejudice or have a personal relationship with any of the parties involved in the case or have a personal stake in how this case is decided?

(e) What was the witness’s attitude toward this case or about giving testimony? 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.

Do not make any decision simply because there were more witnesses on one side than on the other. If you believe it is true, the testimony of a single witness is enough to prove a fact.


New September 2003; Revised April 2004, June 2005, April 2007, December 2012

Directions for Use

This instruction may be given as an introductory instruction or as a concluding instruction after trial. (See CACI No. 5003, Witnesses.)

In the last paragraph, the court may delete inapplicable categories of potential jury bias.

Sources and Authority

  • Evidence Code section 312 provides:

    Except as otherwise provided by law, where the trial is by jury:

    (a) All questions of fact are to be decided by the jury.

    (b) Subject to the control of the court, the jury is to determine the effect and value of the evidence addressed to it, including the credibility of witnesses and hearsay declarants.

  • Considerations for evaluating the credibility of witnesses are contained in Evidence Code section 780:

    Except as otherwise provided by statute, the court or jury may consider in determining the credibility of a witness any matter that has any tendency in reason to prove or disprove the truthfulness of his testimony at the hearing, including but not limited to any of the following:

    (a) His demeanor while testifying and the manner in which he testifies.

    (b) The character of his testimony.

    (c) The extent of his capacity to perceive, to recollect, or to communicate any matter about which he testifies.

    (d) The extent of his opportunity to perceive any matter about which he testifies.

    (e) His character for honesty or veracity or their opposites.

    (f) The existence or nonexistence of a bias, interest, or other motive. (g) A statement previously made by him that is consistent with his testimony at the hearing.

    (h) A statement made by him that is inconsistent with any part of his testimony at the hearing.

    (i) The existence or nonexistence of any fact testified to by him.

    (j) His attitude toward the action in which he testifies or toward the giving of testimony.

    (k) His admission of untruthfulness.

  • Evidence Code section 411 provides that “[e]xcept where additional evidence is required by statute, the direct evidence of one witness who is entitled to full credit is sufficient for proof of any fact.” According to former Code of Civil Procedure section 2061, the jury should be instructed that “they are not bound to decide in conformity with the declarations of any number of witnesses, which do not produce conviction in their minds, against a less number or against a presumption or other evidence satisfying their minds.”
  • The willfully false witness instruction was formerly codified at Code of Civil Procedure section 2061. This statute was repealed in 1965 to avoid giving undue emphasis to this rule compared to other common-law rules. Refusal to give an instruction on this point is not error: “It should certainly not be of importance to tell the ordinary man of the world that he should distrust the statements of a witness whom he believes to be a liar.” (Wallace v. Pacific Electric Ry. Co. (1930) 105 Cal.App. 664, 671 [288 P. 834].)
  • Secondary Sources

    7 Witkin, California Procedure (5th ed. 2008) Trial, § 281

    1A California Trial Guide, Unit 22, Rules Affecting Admissibility of Evidence, § 22.30 (Matthew Bender)

    48 California Forms of Pleading and Practice, Ch. 551, Trial, § 551.122 (Matthew Bender)