Rule of Evidence 404 is one of the more important rules to consider at trial and strategy. Generally, character evidence is not admissible to prove that on a particular occasion a person acted in accordance with a character or trait. This is to prevent what is called "propensity" arguments, or an argument that because someone acted someway in the past, they did so again in this trial or regarding this crime. There are numerous important exceptions and nuances to the rule.

Defendant Character Evidence (404(a)(2)(A))

Under Pa.R.E. 404(a)(2)(A) a defendant may offer evidence of a pertinent trait of the defendant and the prosecutor may offer evidence to rebut it. This evidence usually comes in the form of truthfulness, peacefulness, or law-abidingness, but other character evidence may be permitted (such as a character for being thrifty in an embezzlement case or a good parent in a child abuse case).

A defense attorney has to be careful here, because offering character evidence may open the door to allow the prosecutor to introduce otherwise inadmissible evidence (such as evidence of other crimes).

Victim Character Evidence (404(a)(2)(B))

Under Pa.R.E. 404(a)(2)(B) a defendant may offer evidence of a pertinent trait of an alleged victim, and a prosecutor may offer evidence to rebut it OR offer evidence that the defendant shares the same trait. This exception is most commonly seen in assault cases where the defendant wants to present evidence that the alleged victim has a character trait of violence.

In that example, if the defendant introduces evidence that an alleged victim is a violent person, the Commonwealth may introduce evidence that the defendant was also a violent person.

A particular statutory exception is in the Rape Shield Law, which generally prohibits a Defendant from introducing evidence of the alleged victim's past sexual conduct. The danger is that we generally don't want juries to consider sexual or relationship history in determining the facts of a rape or sexual assault case.

Other Crimes or Acts (404(b))

Under Pa.R.E. 404(b) there are a number of purposes, other than character, for which a person's crimes or acts may be admissible. Examples include motive, opportunity, intent, preparation, plan, knowledge, identity, lack of accident, etc. If admitted the Defendant is entitled to a limiting instruction.

There are numerous other nuances and exceptions to Rule 404 which are rarely mastered by trial attorneys. It is important to note that only a defendant in a criminal case may start the "character war", and that evidence of a pertinent character trait must be in the form of reputation testimony.