Criminal law governs crimes, including felonies, misdemeanors and infractions. Felony punishment can result in a State Prison commitment, misdemeanor punishment in a County Jail commitment and an infraction would involve a fine only. Many crimes (such as grand theft, possession of certain drugs, certain assaults, etc.) may be prosecuted as either felonies or misdemeanors at the discretion of the prosecutor.

In California any person charged with either a felony or a misdemeanor is entitled to a jury trial if he or she so chooses. The standard of proof for crimes is "beyond a reasonable doubt."

Crimes are generally referred to as offenses against the state and are normally prosecuted by the District Attorney (state courts) or the U.S. Attorney (federal courts). A Criminal Defense Attorney defends persons accused of crimes against the charges bought by the prosecutor.