What is propensity evidence?

Propensity evidence is evidence of one crime that is used to show the defendant is more likely to have committed another crime. For example, the prosecution could use evidence of another act of domestic violence to help prove that the defendant committed the current crime of domestic violence. Crimes would have to be similar in nature for propensity evidence to work. The prosecution cannot use a prior DUI to show the defendant currently committed a sex crime. There are two types of crimes, though, where propensity evidence is allowed – sex crimes and domestic violence. Evidence Code section 1108 governs propensity evidence in sex crime charges. (Visit the domestic violence section of our website for a discussion of Evidence Code section 1109).

Evidence Code section 1108

Evidence that a defendant has committed a sex crime at some other time can be used against him to show that he is more likely to have committed a current sex crime, under Evidence Code section 1108. Specifically, Evidence Code section 1108 (a) states:

In a criminal action in which the defendant is accused of a sexual offense, evidence of the defendant’s commission of another sexual offense or offenses is not made inadmissible by Section 1101, if the evidence is not inadmissible pursuant to Section 352.

What this translates into is that the prosecution can use evidence of another sex offense to prove that the defendant committed a current sex offense.

Evidence Code section 1108 further defines what constitutes a qualifying sex offense. The prosecution cannot simply introduce evidence of any crime and call it a “sex offense.” The evidence of another sex offense must meet the definitions laid out by Evidence Code section 1108.

There are some limitations to this rule under Evidence Code section 352, but practically speaking, if there’s evidence that a defendant has a sex crime on his record, the prosecution will introduce that evidence to the jury to help them prove the defendant committed the current sex offense. There is no set time limit on how far in the past the sex offense could be. The prosecution is often allowed to use convictions for sex offenses that are over 10 years old (sometimes even more than 30 years old) to prove current sex crimes. The evidence of another sex offense doesn’t have to be in the past, either. Let’s say a defendant was accused of committing a rape in 2001 but his trial only started in 2003, and during that time, he committed and was convicted of sexual battery in 2002. The prosecution can use evidence of the sexual battery in the rape trial, even though the sexual battery occurred after the alleged rape. Finally, the evidence of the other crime does not even require a conviction. Using the previous example, even if the defendant were acquitted of the sexual battery, the prosecution could still use evidence of the sexual battery in the rape trial! This code section is a powerful tool for the prosecution in sex cases.