Minimum sentences increase the effectiveness of incapacitation.  Incapacitation is one of the 4 basic reasons for punishment. Mandatory minimum sentences keep criminals out of society for a longer period of time than they might otherwise be in jail, thereby reducing their window of opportunity to commit crime. The criminal justice system is obligated to refrain from cruel or unusual punishment, but its main purpose is to protect society from law-breakers through various means of preventing and punishing illegal activity. Mandatory minimum sentences should be proportionate to the severity of the crime, thus satisfying the requirement of humane punishment. Thus mandatory minimum sentencing is a just method of protecting the public.