On a serious note, if someone breaks into your house, you have the right to kill him, no matter why he broke in (thief, rapist, whatever). You also have no right to kill someone entering someone else's house, your only right then is to inform the police. Also, at any time you are in public and someone threatens your life in order to steal from you, you have the right to kill him.
You don't have the right to kill someone who runs and steals you bag, for example. There must have been some immediate threat to your life. In general, "an eye for an eye" kinda thing is applicable, in my opinion. But, I live in Greece, where a burglar can get into my house, I beat him, and I am going to jail because he can sue me because I beat his ass. If I kill him, I am going in for life, because I commited a homicide.