Penns Creek Juvenile Law Lawyer, Pennsylvania

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 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 procedure in which the police place a suspect in a line with a group of other people and ask an eyewitness to the crime to identify the person he saw at the crime scene. The police are supposed to choose similar-looking people to appear with the suspect. If the suspect alone matches the physical description of the perpetrator, evidence of the identification can be attacked at trial. For example, if the robber is described as a Latino male, and the suspect, a Latino male, is placed in a lineup with ten white males, a witness' identification of him as the robber will be challenged by the defense attorney.

A formal investigation -- governed by court rules -- that is conducted before trial. Discovery allows one party to question other parties, and sometimes witnesses. It also allows one party to force the others to produce requested documents or other physical evidence. The most common types of discovery are interrogatories, consisting of written questions the other party must answer under penalty of perjury, and depositions, which involve an in-person session at which one party to a lawsuit has the opportunity to ask oral questions of the other party or her witnesses under oath while a written transcript is made by a court reporter. Other types of pretrial discovery consist of written requests to produce documents and requests for admissions, by which one party asks the other to admit or deny key facts in the case. One major purpose of discovery is to assess the strength or weakness of an opponent's case, with the idea of opening settlement talks. Another is to gather information to use at trial. Discovery is also present in criminal cases, in which by law the prosecutor must turn over to the defense any witness statements and any evidence that might tend to exonerate the defendant. Depending on the rules of the court, the defendant may also be obliged to share evidence with the prosecutor.

The money posted by a 'bondsman' for a defendant who cannot afford his bail. The defendant pays a certain portion, usually 10%. If the defendant fails to appear for a court hearing, the judge can issue a warrant for his arrest and threaten to 'forfeit,' or keep, the money if the defendant doesn't appear soon. Usually, the bondsman will look for the defendant and bring him back, forcefully if necessary, in order to avoid losing the bail money.

A formal accusation of criminal activity. The prosecuting attorney decides on the charges, after reviewing police reports, witness statements and any other evidence of wrongdoing. Formal charges are announced at an arrested person's arraignment.

A decision by the jury to acquit a defendant who has violated a law that the jury believes is unjust or wrong. Jury nullification has always been an option for juries in England and the United States, although judges will prevent a defense lawyer from urging the jury to acquit on this basis. Nullification was evident during the Vietnam war (when selective service protesters were acquitted by juries opposed to the war) and currently appears in criminal cases when the jury disagrees with the punishment--for example, in 'three strikes' cases when the jury realizes that conviction of a relatively minor offense will result in lifetime imprisonment.

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.