De Pere Juvenile Law Lawyer, Wisconsin

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 minor violation of the law that is punishable only by a fine--for example, a traffic or parking ticket. Not all vehicle-related violations are infractions, however--refusing to identify oneself when involved in an accident is a misdemeanor in some states.

A seldom-used test for criminal insanity that labels the person insane if he could not control his actions when committing the crime, even though he knew his actions were wrong.

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 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.

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 exception to the general rule that a police officer needs an arrest warrant before he can enter a home to make an arrest. If a felony has just occurred and an officer has chased a suspect to a private house, the officer can forcefully enter the house in order to prevent the suspect from escaping or hiding or destroying evidence.

A situation in which the police detain a person in a manner that, to any reasonable person, makes it clear she is not free to leave. A person can be 'under arrest' even though the police have not announced it; nor are handcuffs or physical restraint necessary. Questioning an arrested person about her involvement in or knowledge of a crime must be preceded by the Miranda warnings if the police intend to use the answers against the person in a criminal case. If the arrested person chooses to remain silent, the questioning must stop.