California Evidence Code 1101 is the state’s character evidence rule: it bars using a person’s character, reputation, or prior acts to prove they acted a certain way on a specific occasion. The rule keeps a jury focused on what happened during the charged incident rather than on whether the defendant seems like the “type of person” who would do it. But subdivision (b) of the statute, along with several companion sections, opens real exceptions. Prior acts can come in to show things like motive, intent, plan, or identity, and in sexual offense and domestic violence prosecutions they can come in as evidence of propensity itself.
What Section 1101(a) Prohibits
Subdivision (a) is the general ban. Character evidence is inadmissible when offered to prove conduct on a specific occasion, whether it takes the form of opinion testimony, reputation evidence, or specific past acts.1California Legislative Information. California Evidence Code 1101 If you’re on trial for theft, the prosecution cannot call witnesses to say you’ve always been dishonest, or introduce evidence of prior thefts, just to argue you probably stole again.
The concern is practical. Once jurors hear a defendant has a history of similar behavior, it becomes hard to evaluate the current charge on its own merits. Jurors start thinking “this person did it before, so they probably did it again,” which is exactly the reasoning the rule exists to prevent.
When Prior Acts Come In Under Section 1101(b)
Subdivision (b) is where most of the fighting happens. Prior crimes, civil wrongs, or other acts are admissible when relevant to prove something other than a general tendency to commit that kind of act. The statute lists several permitted purposes: motive, opportunity, intent, preparation, plan, knowledge, identity, and absence of mistake or accident. It also allows evidence showing that a defendant in a sexual assault case did not reasonably believe the victim consented.1California Legislative Information. California Evidence Code 1101
That list is illustrative, not exhaustive. Courts have admitted prior-act evidence for other non-propensity purposes as long as it’s logically relevant to something besides character. The question is always whether the evidence is offered to prove a specific disputed fact or merely to paint the defendant as a bad person.
A few examples of how those purposes play out:
- Intent. If a defendant claims a shooting was accidental, the prosecution might introduce a prior deliberate shooting to show the defendant knew what pulling the trigger would do.
- Plan or scheme. Evidence that a defendant used the same unusual method in a prior crime can show the charged offense was part of a deliberate pattern rather than coincidence.
- Identity. When the question is who committed the crime, prior acts with a highly distinctive method can link the defendant to the charged offense like a signature.
- Motive. Evidence of a prior conflict between the defendant and victim can establish why the defendant would have committed the charged act.
- Absence of mistake. If a pharmacist is charged with dispensing the wrong medication, evidence that the same “mistake” happened repeatedly with the same drug makes accident less plausible.
How Much Similarity Is Required
The California Supreme Court’s decision in People v. Ewoldt (1994) set the framework courts still use to test whether a prior act is similar enough to the charged offense to come in under 1101(b). Different purposes demand different degrees of resemblance.2Justia. People v. Ewoldt (1994)
The least similarity is needed to prove intent. When mental state is disputed, a prior act that produced a similar result tends to negate claims of accident or innocent intent, and the uncharged act just needs to be similar enough to support the inference that the defendant likely had the same intent both times.
A greater degree of similarity is required for common design or plan. The prior and current acts must share enough common features that they’re naturally explained as part of the same overarching scheme. Similar results aren’t enough; the method and circumstances need to overlap in ways that suggest a deliberate pattern.
The highest bar applies to identity. The pattern and characteristics of the crimes must be so unusual and distinctive as to function like a signature, making it reasonable to conclude the same person committed both. Ordinary similarities won’t do.2Justia. People v. Ewoldt (1994)
The Section 352 Filter
Clearing 1101(b) doesn’t guarantee admission. Evidence Code Section 352 gives judges discretion to exclude relevant evidence when its probative value is substantially outweighed by the probability of undue prejudice, confusion of issues, or misleading the jury.3California Legislative Information. California Evidence Code 352
Courts weigh how important the disputed fact is, how strongly the prior act proves it, how remote the prior act is in time, and whether a limiting instruction can realistically prevent misuse. A prior act from fifteen years ago that only weakly resembles the charged offense faces a much steeper climb than a strikingly similar act from last year. Many character evidence battles are won or lost here rather than at the 1101(b) stage: a prosecutor may satisfy relevance and still lose the evidence at 352 because the prior act is more inflammatory than probative.
Good Character Evidence a Defendant Can Offer
Section 1101(a) states that its ban is subject to several companion statutes. One of them, Evidence Code 1102, lets criminal defendants introduce evidence of their own good character to argue they acted consistently with that character during the charged incident. A defendant accused of assault can call witnesses to testify to a peaceful reputation.4California Legislative Information. California Evidence Code 1102
Two limits matter. The evidence must be in the form of opinion or reputation testimony, not a recital of specific good deeds. And once a defendant opens this door, the prosecution can walk through it. Put your peaceful character at issue and the prosecution gets to introduce rebuttal evidence of your violent character in the same forms. This is sometimes called the “mercy rule” because only the defendant can activate it, and experienced defense attorneys think carefully before doing so, because the rebuttal sometimes hurts more than the good-character showing helps.
Victim Character in Self-Defense Cases
Evidence Code 1103 lets a defendant introduce evidence of the victim’s character or specific past conduct to argue the victim acted in conformity with that character. The classic use is self-defense: a defendant claiming the victim attacked first can present evidence of the victim’s history of violence.5California Legislative Information. California Evidence Code 1103
Unlike 1102, Section 1103 permits evidence of specific instances of the victim’s conduct, not just reputation and opinion. A defendant can point to particular fights the victim started or threats the victim made.
The tradeoff is significant. Once a defendant introduces evidence of the victim’s violent character, subdivision (b) of Section 1103 lets the prosecution introduce evidence of the defendant’s own character for violence. That creates a strategic calculation for every self-defense case: does showing the victim’s violent past outweigh the risk of the jury hearing about the defendant’s own history?
Sexual Offense Cases: Section 1108
Evidence Code 1108 is one of the most consequential exceptions to the character evidence ban. In a criminal case charging a sexual offense, the prosecution can introduce evidence that the defendant committed other sexual offenses, and the jury may consider those prior offenses as evidence of the defendant’s disposition to commit sexual crimes. That is a direct exception to the propensity rule at the heart of 1101(a).6California Legislative Information. California Evidence Code 1108
Section 352 still applies. The judge must decide whether the probative value of the prior sexual offense evidence is substantially outweighed by the danger of undue prejudice. The prosecution must disclose the evidence to the defense before trial, including witness statements or a summary of expected testimony. The statutory definition of “sexual offense” is broad, covering offenses ranging from sexual battery and rape to child molestation and distribution of child sexual abuse material.
Domestic Violence Cases: Section 1109
Evidence Code 1109 works on the same principle as 1108 but applies to domestic violence prosecutions. When a defendant is charged with a domestic violence offense, the prosecution can introduce evidence of other acts of domestic violence, and the jury may consider that evidence as showing propensity. This is a true propensity exception, not limited to the non-character purposes in 1101(b).7California Legislative Information. California Evidence Code 1109
Section 1109 includes a time limit that 1108 does not. Evidence of prior domestic violence acts occurring more than ten years before the charged offense is generally inadmissible, unless the court finds admission serves the interest of justice. The statute also requires pretrial disclosure, and all evidence remains subject to the 352 balancing test.
Habit Is Not Character
Evidence Code 1105 draws a line that trips up many people. Habit evidence is admissible to prove conduct on a specific occasion, even though character evidence is not. Character describes a general disposition (she’s a careful person); habit describes a specific, repeated response to a particular situation (she always checks her mirrors before changing lanes).8California Legislative Information. California Evidence Code 1105
To qualify as habit, the behavior must be specific enough and repeated frequently enough that it’s essentially automatic. A business that always requires two signatures on checks over a certain amount has a routine practice. A driver who always signals before turning has a habit. Courts view habit evidence as more reliable than character evidence because uniformity makes it a stronger predictor of what someone actually did. The challenge is proving the behavior truly rises to the level of a habit rather than an occasional tendency, which falls back into character territory that 1101(a) forbids.
Jury Instructions and Stipulation Strategy
When uncharged-act evidence comes in under 1101(b), California courts use CALCRIM 375 to guard against misuse. The instruction tells jurors the prosecution must prove the uncharged act by a preponderance of the evidence (a lower standard than beyond a reasonable doubt), that the evidence may only be considered for the specific limited purpose for which it was admitted, and that jurors may not treat it as proof of bad character or a disposition to commit crime.9Justia. CALCRIM No. 375 – Evidence of Uncharged Offense to Prove Identity, Intent, Common Plan, etc.
The instruction also reminds jurors that even believing the defendant committed the uncharged act is not enough to prove guilt; the prosecution must still prove every element of the charged offense beyond a reasonable doubt. Trial courts are required to give this instruction when requested, and in rare cases where uncharged-act evidence dominates the trial, the court may need to give it even without a request.
Defense attorneys have another tool: offering to stipulate to the element the prosecution wants to prove with the prior-act evidence. If the defendant concedes intent, for example, the argument for admitting prior acts weakens because the fact is no longer disputed. The prosecution doesn’t have to accept the stipulation, but a rejected offer can shift the 352 analysis by making the prior-act evidence look cumulative and less necessary.
Civil Cases
Section 1101 governs civil litigation too, and the propensity ban applies with the same force. The narrow exception is “character in issue” cases, where a person’s character is itself an element of a claim or defense. Negligent entrustment is the classic example: if you lend your car to someone you know is a reckless driver, the borrower’s driving history is directly relevant to whether you were negligent in handing over the keys. Outside these narrow situations, civil cases follow the same general prohibition against propensity reasoning that governs criminal trials.