Attendant circumstances are a legal concept which Black's Law Dictionary defines as the "facts surrounding an event." With some crimes, it must be proven that certain events occurred (or certain facts are true) in order for a defendant to be found guilty. For example: if a law states: "It is illegal to frown at the police"; then in order for a person to be found guilty of this crime, it would have to be proven that they had frowned "at the police". Likewise, a law might define a burglary to be a more serious felony if it occurred in a habitation. When verification of an attendant circumstance increases the penalty for a crime, it is known as an aggravating circumstance; when verification of an attendant circumstance decreases the penalty, it is known as a mitigating circumstance.