This case is mentioned in Street Law, Chapter 1. However, in this case, there is not a law suit being brought against Dudley and Stephens. Instead, they are being tried for murder.
If you are asking if the two men should be convicted of murder, I think that they absolutely should. There is nothing that says you can kill someone else to save your own life unless they are threatening to kill you--you can't just kill someone because it will be beneficial to you.
If there were a lawsuit involved in this case, it might be for wrongful death. If such a case were brought against the defendants, I think that the plaintiffs (injured party) would win. Dudley and Stephens clearly caused the other's death in circumstances where their actions were wrong.
So whether this is a criminal case or a tort (lawsuit), Dudley and Stephens ought to lose.