Self Defense

You are lying in bed in the middle of the night; you are awakened by a soft noise. you open your sleepy eyes, there is an intruder in your bedroom. Is he dangerous? You have no idea. Can you shoot him? (let's just say you believe in the second amendment).

In general, the law says, that if you think your life is in danger you may protect your life by killing the intruder.
 
The problem is that the law does not give an exact definition to what genuine danger is. At 2:00am, having just been awakened, frightened and  in the dark, it is difficult to make such an important decision in a split second. The problem is even greater: the jury sitting in judgment may not understand the threat you felt at that moment. Sitting in the safety of the court house they may feel that you used too much force.

So the bottom line is that the law leaves you on your own in the dark, literally.

Here is what the Talmud says:
If someone is in your bedroom (as long as he is not trying to escape) you can kill him. Because the intruder expects you to be there, you can assume that he is prepared to use force, you therefore have the right to protect yourself.

Now take a look at this interesting detail:
If you find an intruder in a place were he does not expect to see you, such as a place of business after business hours, you may not kill the intruder. The reason for this is, that since the intruder did not expect you to be there you can't assume that the intruder is prepared to use violence against you. Therefore you have no right to harm him.