What is Mens Rea?

Latin for "guilty mind."  Many criminal offenses (e.g., murder) contain a guilty mind requirement.  Thus, in order for a person to be found guilty of these crimes, the prosecutor must prove that the person had the requisite criminal intent when committing the crime.

Compare to "strict liability" crimes that do not require mens rea.  For instance, statutory rape is most jurisdictions is a strict liability crime that does not require the necessary guilty mind element (i.e., a guy can be convicted of statutory rape even if he believed the girl to be over eighteen years of age).