Winn Juvenile Law Lawyer, Maine

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.

The privilege that allows the president and other high officials of the executive branch to keep certain communications private if disclosing those communications would disrupt the functions or decisionmaking processes of the executive branch. As demonstrated by the Watergate hearings, this privilege does not extend to information germane to a criminal investigation.

The making of statements that might expose you to criminal prosecution, either now or in the future. The 5th Amendment of the U.S. Constitution prohibits the government from forcing you to provide evidence (as in answering questions) that would or might lead to your prosecution for a crime.

A mental defect or disease that makes it impossible for a person to understand the wrongfulness of his acts or, even if he understands them, to ditinguish right from wrong. Defendants who are criminally insane cannot be convicted of a crime, since criminal conduct involves the conscious intent to do wrong -- a choice that the criminally insane cannot meaningfully make. See also irresistible impulse; McNaghten Rule.

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.

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.

A peace officer for a particular geographic area -- most often a rural county -- who commonly has the power to serve legal papers, arrest lawbreakers and keep the peace. Depending on the state, a constable may be similar to a marshal or sheriff.

Someone who intentionally helps another person commit a felony by giving advice before the crime or helping to conceal the evidence or the perpetrator. An accessory is usually not physically present during the crime. For example, hiding a robber who is being sought by the police might make you an 'accessory after the fact' to a robbery. Compare accomplice.

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.