Self-Defense: Definition & Laws

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  • 0:05 Self-Defense Requirements
  • 0:58 The Threat Must be Imminent
  • 1:47 The Fear of Harm Must…
  • 2:33 The Response Must be…
  • 3:09 Castle Doctrine &…
  • 3:57 Lesson Summary
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Lesson Transcript
Instructor: Amy Bonn

Amy has taught college and law school writing courses and has a master's degree in English and a JD.

Self-defense, with respect to criminal law, involves the justified use of force to protect oneself from harm. Find out in this lesson when, how, and where one can defend oneself under the law.

Self-Defense Requirements

We've all had to justify things from time to time, whether it's to ourselves or others. Perhaps we've had to justify taking that one last cookie or staying up late to catch the ending of a movie. When we justify something, we're making the case that doing something is okay.

In criminal law, there are very few ways that the use of force, even deadly force, can be justified, or seen as a right under the law. Self-defense is the justified use of force to protect oneself from harm. A person who invokes self-defense must not have been the aggressor in the situation that led to the need to defend him or herself. While the concept of self-defense might seem pretty straightforward, the key things to focus on are when, how, and where one can defend oneself justifiably under the law.

The Threat Must be Imminent

When a person has invoked self-defense as a reason to justify having killed another person, for example, it must be determined whether the perceived threat of harm was imminent. Something that is imminent is about to happen immediately.

So if, for example, Ted forgets to record his roommate Bob's favorite show, and an enraged Bob runs at Ted with a knife, the threat to Ted would be imminent. In other words, Ted would have to act fast to defend himself. If, however, an enraged Bob tells Ted that once he gets paid the following week, he will go out and buy a pricy knife to stab Ted with, then Ted would not be facing an imminent threat, and would not be justified in reacting by killing Bob. Self-defense would not apply in that case.

The Fear of Harm Must be Reasonable

Additionally, in order to be justified in using force to defend oneself, one's fear of being imminently harmed must be reasonable, meaning that a reasonable and prudent person would have deemed the threat to be real.

Let's say Ted leaves all of his dirty dishes in the sink, and an annoyed Bob tells him, 'I could kill you for never loading the dishwasher.' Assuming that Bob is not a violent guy and was not behaving in a threatening way toward his roommate (roommates often say off-the-cuff things to each other), Ted would not be justified in running over to Bob and strangling him to death, and if he did, self-defense wouldn't apply here, as it wouldn't be reasonable for Ted to assume that Bob was about to kill him.

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