Jamestown Juvenile Law Lawyer, Ohio, page 3

An affirmative defense to a crime. Self-defense is the use of reasonable force to protect oneself from an aggressor. Self-defense shields a person from criminal liability for the harm inflicted on the aggressor. For example, a robbery victim who takes the robber's weapon and uses it against the robber during a struggle won't be liable for assault and battery since he can show that his action was reasonably necessary to protect himself from imminent harm.

A rule of evidence that disallows the use of illegally obtained evidence in criminal trials. For example, the exclusionary rule would prevent a prosecutor from introducing at trial evidence seized during an illegal search.

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.

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.

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 intent to produce the precise consequences of the crime, including the intent to do the physical act that causes the consequences. For example, the crime of larceny is the taking of the personal property of another with the intent to permanently deprive the other person of the property. A person is not guilty of larceny just because he took someone else's property; it must be proven that he took it with the purpose of keeping it permanently.

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.

The making of statements that might expose you to criminal prosecution, either now or in the future. The 5th Amendment of the U.S. Constitution prohibits the government from forcing you to provide evidence (as in answering questions) that would or might lead to your prosecution for a crime.