In exceptional circumstances, a person is entitled to break the law if it is necessary to prevent a larger harm. The necessity defense (sometimes referred to as the rule of the lesser evil or the emergency defense) recognizes that a criminal act is sometimes necessary to prevent greater harm. Necessity is very rarely a viable defense, because the government has an interest in discouraging people from breaking the law. Therefore, it’s unusual for a defendant to be able to satisfy the elements of necessity.
In order for a defendant to be found not guilty pursuant to the necessity defense, three elements must be present:
If the defendant presents some evidence on each element of the necessity defense, the Commonwealth bears the burden of proving beyond a reasonable doubt that the defendant was not acting out of necessity.
A defendant can only be convicted of a crime if his actions are the result of free will. Therefore, if a defendant violated the law under duress, he cannot be found guilty.
Three elements must be established by the defendant in order for a duress defense to apply.
Just as with the necessity defense, if the defendant presents evidence on each element of the duress defense, the Commonwealth bears the burden of proving, beyond a reasonable doubt, that the defendant was not under duress when he committed the crime.
A duress defense is available to defendants who were acting to prevent threatened harm to a third party.
Defendants who have been prior victims of domestic violence are generally entitled to introduce evidence of their domestic violence history to establish the reasonableness of their conduct in committing criminal acts. For example, a woman who injures her abusive husband during a fight can probably introduce evidence of his prior abuse to establish she defended herself in a reasonable manner.