Bristol Juvenile Law Lawyer, England

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.

The killing of one human being by the act or omission of another. The term applies to all such killings, whether criminal or not. Homicide is considered noncriminal in a number of situations, including deaths as the result of war and putting someone to death by the valid sentence of a court. Killing may also be legally justified or excused, as it is in cases of self-defense or when someone is killed by another person who is attempting to prevent a violent felony. Criminal homicide occurs when a person purposely, knowingly, recklessly or negligently causes the death of another. Murder and manslaughter are both examples of criminal homicide.

Circumstances that increase the seriousness or outrageousness of a given crime, and that in turn increase the wrongdoer's penalty or punishment. For example, the crime of aggravated assault is a physical attack made worse because it is committed with a dangerous weapon, results in severe bodily injury or is made in conjunction with another serious crime. Aggravated assault is usually considered a felony, punishable by a prison sentence.

A type of behavior that is has been defined by the state, as deserving of punishment which usually includes imprisonment. Crimes and their punishments are defined by Congress and state legislatures.

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 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.

To intentionally destroy, obliterate or strike out records or information in files, computers and other depositories. For example, state law may allow the criminal records of a juvenile offender to be expunged when he reaches the age of majority, to allow him to begin his adult life with a clean record. Or, a company or government agency may routinely expunge out-of-date records to save storage space.

Latin for 'we shall no longer prosecute.' At trial, this is an entry made on the record by a prosecutor in a criminal case stating that he will no longer pursue the matter. An entry of nolle prosequi may be made at any time after charges are brought and before a verdict is returned or a plea entered. Essentially, it is an admission on the part of the prosecution that some aspect of its case against the defendant has fallen apart. Most of the time, prosecutors need a judge's A1:C576 to 'nol-pros' a case. (See Federal Rule of Criminal Procedure 48a.) Abbreviated 'nol. pros.' or 'nol-pros.'

A method of paying a lawyer for legal representation by which, instead of an hourly or per job fee, the lawyer receives a percentage of the money her client obtains after settling or winning the case. Often contingency fee agreements -- which are most commonly used in personal injury cases -- award the successful lawyer between 20% and 50% of the amount recovered. Lawyers representing defendants charged with crimes may not charge contingency fees. In most states, contingency fee agreements must be in writing.