Mitigating circumstances are factors that partially explain or excuse behavior. They are often referred to in the legal context as factors that make a crime more understandable. These circumstances are not an absolute excuse and do not mean that no culpability will be attached to the actions; they simply mean that the actions are viewed as less egregious in light of the circumstances.
The opposite of this is aggravating factors. Aggravating factors are those that make a crime seem more egregious, such as prior felony convictions or choosing an especially vulnerable victim. Such conditions can make the penalty for a crime more stringent.
Mitigating factors, on the other hand, can at times lessen the penalties associated with a crime. For example, if a person walks in on his spouse while she is having an affair and kills her, the fact that he caught her engaged in infidelity could be considered a mitigating circumstance. He is not excused from killing her in the eyes of the law, but his crime is seen as more understandable.
When such circumstances are present, the penalties associated with the crime can be less stringent. For example, in the situation described above, the person who walked in on his spouse would normally have been guilty of first or second degree murder as a result of the killing. Since he caught her in the act of infidelity, however, he would be tried only for manslaughter in some jurisdictions.
The law allows circumstances to occasionally mitigate penalties for crimes because certain things make a crime more understandable. It is, in a sense, a public policy exception to penalties associated with a crime. It is the law's version of realizing that some things make illegal behavior more acceptable.
There must still be penalties for the behavior despite the circumstances that seem to mitigate the actions because the law does not want to encourage vigilante justice. For example, the law cannot void all penalties associated with a man killing his unfaithful spouse, otherwise everyone might take justice into their own hands. Still, the law recognizes that it is somewhat understandable that he would kill his wife under these circumstances.
Common examples include crimes of passion or incapacitation. The example of a man walking in on an unfaithful wife would be a crime of passion. Diminished capacity to understand the circumstances of the crime, or the victim's consent to the criminal behavior, can also be considered a mitigating circumstance.
