Character A and B are lost at sea together, after a couple of the days the water supply becomes an issue and in order to prolong his own life A knocks B unconscious and dumps him over board.
Now, I'd like for this to lead to some type of investigation - A will be telling the truth about the events because he is certain that it will fall under self defence.
I've googled different variations of self-defense, kill, murder, justifiable kill etc. I've also checked some law texts but the problem with that is that I need someone to explain the meaning of the text... Self defence in English law is using reasonable force against an unjust threat (http://en.wikipedia.org/wiki/Self-defence_in_English_law), so what is "unjust"? Would it apply to my scenario