Roy Juvenile Law Lawyer, Montana

A rule of evidence that disallows the use of illegally obtained evidence in criminal trials. For example, the exclusionary rule would prevent a prosecutor from introducing at trial evidence seized during an illegal search.

In criminal cases, a group that decides whether there is enough evidence to justify an indictment (formal charges) and a trial. A grand jury indictment is the first step, after arrest, in any formal prosecution of a felony.

One of the most sacred principles in the American criminal justice system, holding that a defendant is innocent until proven guilty. In other words, the prosecution must prove, beyond a reasonable doubt, each element of the crime charged.

The amount and quality of information police must have before they can arrest or search without a warrant or that a judge must have before she will sign a search warrant allowing the police to conduct a search or arrest a suspect. Reliable information must show that it's more likely than not that a crime has occurred and the suspect is involved.

A crime that occurs when one person tries to physically harm another in a way that makes the person under attack feel immediately threatened. Actual physical contact is not necessary; threatening gestures that would alarm any reasonable person can constitute an assault. Compare battery.

A decision by a judge or jury that a defendant in a criminal case is not guilty of a crime. An acquittal is not a finding of innocence; it is simply a conclusion that the prosecution has not proved its case beyond a reasonable doubt.

A plea entered by the defendant in response to being charged with a crime. If a defendant pleads nolo contendere, she neither admits nor denies that she committed the crime, but agrees to a punishment (usually a fine or jail time) as if guilty. Usually, this type of plea is entered because it can't be used as an admission of guilt if a civil case is held after the criminal trial.

An affirmative defense to a crime. Self-defense is the use of reasonable force to protect oneself from an aggressor. Self-defense shields a person from criminal liability for the harm inflicted on the aggressor. For example, a robbery victim who takes the robber's weapon and uses it against the robber during a struggle won't be liable for assault and battery since he can show that his action was reasonably necessary to protect himself from imminent harm.