Kimball Juvenile Law Lawyer, West Virginia

The mental component of criminal liability. To be guilty of most crimes, a defendant must have committed the criminal act (the actus reus) in a certain mental state (the mens rea). The mens rea of robbery, for example, is the intent to permanently deprive the owner of his property.

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 party's job of convincing the decisionmaker in a trial that the party's version of the facts is true. In a civil trial, it means that the plaintiff must convince the judge or jury 'by a preponderance of the evidence' that the plaintiff's version is true -- that is, over 50% of the believable evidence is in the plaintiff's favor. In a criminal case, because a person's liberty is at stake, the government has a harder job, and must convince the judge or jury beyond a reasonable doubt that the defendant is guilty.

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.

A quaint phrase that refers to the recording of an arrested person's name, age, address and reason for arrest when that person is brought to jail and placed behind bars. Nowadays, the book is likely to be a computer. Usually, a mug shot and fingerprints are taken, and the arrestee's clothing and personal effects are inventoried and stored.

Latin for 'You have the body.' A prisoner files a petition for writ of habeas corpus in order to challenge the authority of the prison or jail warden to continue to hold him. If the judge orders a hearing after reading the writ, the prisoner gets to argue that his confinement is illegal. These writs are frequently filed by convicted prisoners who challenge their conviction on the grounds that the trial attorney failed to prepare the defense and was incompetent. Prisoners sentenced to death also file habeas petitions challenging the constitutionality of the state death penalty law. Habeas writs are different from and do not replace appeals, which are arguments for reversal of a conviction based on claims that the judge conducted the trial improperly. Often, convicted prisoners file both.