Yamaguchi Juvenile Law Lawyer, Japan

The earliest and most common test for criminal insanity, in which a criminal defendant is judged legally insane only if he could not distinguish right from wrong at the time he committed the crime. For example, a delusional psychotic who believed that his assaultive acts were in response to the will of God would not be criminally responsible for his acts.

A lawyer appointed by the court and paid by the county, state, or federal government to represent clients who are charged with violations of criminal law and are unable to pay for their own defense.

A document issued by a judge or magistrate that authorizes the police to arrest someone. Warrants are issued when law enforcement personnel present evidence to the judge or magistrate that convinces her that it is reasonably likely that a crime has taken place and that the person to be named in the warrant is criminally responsible for that crime.

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 term that describes vigorous questioning, usually by the police of a suspect in custody. Other than providing his name and address, the suspect is not obligated to answer the questions, and the fact that he has remained silent generally cannot be used by the prosecution to help prove that he is guilty of a crime. If the suspect has asked for a lawyer, the police must cease questioning. If they do not, they cannot use the answers against the suspect at trial.

A crime consisting of physical contact that is intended to harm someone. Unintentional harmful contact is not battery, no mater how careless the behavior or how severe the injury. A fist fight is a common battery; being hit by a wild pitch in a baseball game is not.

A serious crime (contrasted with misdemeanors and infractions, less serious crimes), usually punishable by a prison term of more than one year or, in some cases, by death. For example, murder, extortion and kidnapping are felonies; a minor fist fight is usually charged as a misdemeanor, and a speeding ticket is generally an infraction.

A negotiation between the defense and prosecution (and sometimes the judge) that settles a criminal case. The defendant typically pleads guilty to a lesser crime (or fewer charges) than originally charged, in exchange for a guaranteed sentence that is shorter than what the defendant could face if convicted at trial. The prosecution gets the certainty of a conviction and a known sentence; the defendant avoids the risk of a higher sentence; and the judge gets to move on to other cases.

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.