Gilson Juvenile Law Lawyer, Illinois

The amount and quality of information police must have before they can arrest or search without a warrant or that a judge must have before she will sign a search warrant allowing the police to conduct a search or arrest a suspect. Reliable information must show that it's more likely than not that a crime has occurred and the suspect is involved.

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 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.

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.

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.

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.

The defendant's formal answer to criminal charges. Typically defendants enter one of the following pleas: guilty, not guilty or nolo contendere. A plea is usually entered when charges are formally brought (at arraignment).

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.

Testimony or other evidence that fails to meet state or federal court rules governing the types of evidence that can be presented to a judge or jury. The main reason why evidence is ruled inadmissible is because it falls into a category deemed so unreliable that a court should not consider it as part of a deciding a case --for example, hearsay evidence, or an expert's opinion that is not based on facts generally accepted in the field. Evidence will also be declared inadmissible if it suffers from some other defect--for example, as compared to its value, it will take too long to present or risks enflaming the jury, as might be the case with graphic pictures of a homicide victim. In addition, in criminal cases, evidence that is gathered using illegal methods is commonly ruled inadmissible. Because the rules of evidence are so complicated (and because contesting lawyers waste so much time arguing over them) there is a strong trend towards using mediation or arbitration to resolve civil disputes. In mediation and arbitration, virtually all evidence can be considered. See evidence, admissible evidence.