Mens rea – From latin for “guilty mind.” Many serious crimes require the proof of “mens rea” before a person can be charged with a conviction. 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.

See also: http://www.britannica.com/EBchecked/topic/375243/mens-rea .