A circumstance is a unique aspect of a particular crime's commission. It is an accompanying or accessory fact, event, or condition, such as a piece of evidence that suggests the probability of an event.
Aggravating Circumstance is a fact or situation that increases the degree of liability or culpability for a criminal act. It is also a fact or situation that relates to a criminal offense or defendant and is considered by the court in determining punishment. Aggravating circumstances usually increase the level of punishment, and mitigating circumstances reduce it.
Mitigating Circumstance is a fact or situation that does not excuse or justify a criminal act but reduces the culpability of a person who committed the offense and helps to reduce the punishment.
Exigent Circumstance is a fact or situation wherein a law enforcement officer who has probable cause must take immediate steps to make an arrest, search, or seizure without a warrant because someone's life or safety is threatened, because there is a risk of imminent escape by a suspect or because evidence is about to be destroyed.