Self-defense is, understandably, one of the murkiest topics in criminal law. This is because judges and the legislature are stuck trying to compromise between complex, competing interests. On the one hand, having a right to defend oneself from a mugging or other attack when doing so is necessary makes a lot of sense. On the other, self-defense laws encourage people to take things into their own hands rather than using the police, who are trained to handle such circumstances. This can lead to violence getting out of hand unnecessarily. Self-defense laws are designed to strike a balance between these goals.
Most states have a general rule that covers self-defense when defending people, and another when defending property. When defending themselves, people are allowed to use force to the extent necessary to defend either themselves or another person from a similar amount of force. The law with regard to defending people also makes a special rule for the use of deadly force. The law only allows the use of force in instances where the person reasonably believes it is necessary to prevent the death or great bodily harm of him or herself or someone else or in the resistance of a forcible felony, such as kidnapping.
This formulation of the law complicates one of the most controversial elements of self-defense laws, whether the defender has a duty to retreat before using deadly force. In some states, people are not allowed to use deadly force if they know that they can escape with complete safety. In other states, that duty does not exist. However, there have been cases of juries finding that it was not reasonable to believe that the use of deadly force was necessary if the person could have retreated.
The rule for the defense of property is similar to the above. People are allowed to use force that they reasonably believe is necessary to prevent interference with their property. The deadly force exception here is considerably more narrow. The person may only use deadly force to defend property if he or she is resisting a forcible felony. There is one exception to the deadly force rule, which applies to people defending their homes. This exception is known as the Castle Doctrine.
The Castle Doctrine is an expanded right to the defense of property and self when a person is in his or her own home. The law does not expect people to surrender their homes to criminals, so it expands the allowable use of force there. People are allowed to use deadly force in their own homes if someone is violently trying to enter and the person trying to enter intends to assault someone in the home, or if the person in the home reasonably believes that it is necessary to prevent a crime.
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