[Mouse]

Nobody gets put in prison for defending themselves as long as the force and methods of self defence used are reasonable.

Here's an example:-

Someone comes up to me in the street and punches me. I take a swing back, connect and he falls over. I walk away, he gets charged with assault or some other public order offence.

As above but when he falls over, I run up to him and stamp repeatedly on his head. He dies, I get charged with either murder or culpable homicide.

The difference is that in the second example, the force I used was far beyond what was reasonable given the circumstances and in a civilised society, I believe it's the judicial system or legislature to decide what constitutes reasonableness in any particular situation, not the individual.