Mens rea
Latin for "guilty mind." Many serious crimes require the proof of "mens rea" before a person can be convicted. In other words, the prosecution must prove not only that the accused committed the offence but that he (or she) did it knowing that it was prohibited; that their act (or omission) was done with an intent to commit a crime.

Minor
A person who is legally underage. It varies between 21 and 18 years of age. Each state/province sets an age threshold at which time a person is invested with all legal rights as an adult. For many new adults, this may mean access to places serving alcohol and the right to purchase and consume alcohol, smoke cigarettes and drive a car. But there are many other legal rights which a minor does not have such as, in some states, the right to own land, to sign a contract or to get married.

Misdemeanor
( USA ) A crime of lesser seriousness than a felony where the punishment might be a fine or prison for less than one year.

Mistrial
A partial or complete trial which is found to be null and void and of no effect because of some irregularity. The sudden end of trial before it would ordinarily end because of some reason which invalidates it. Once a mistrial is declared, the situation is as if the trial had never occurred. Some common reasons for a mistrial include a deadlocked jury, the death of a juror or a serious procedural and prejudicial mistake made at the trial which cannot be corrected.

Mitigating circumstances
These are facts that, while not negating an offence or wrongful action, tend to show that the defendant may have had some grounds for acting the way he/she did. For example, assault , though provoked, is still assault but provocation may constitute mitigating circumstances and allow for a lesser sentence.