It is unethical to kill someone if you have other options at your disposal.
That said, it is ethical to kill them if you have no options and killing them perserves your life or someone elses.
Everyone must take inventory of their own situation and own skills and decide what they must do.
Even if the court rules that it was self defense. Spiritually and philosophically you still must be true to yourself, since that is the person you must ultimately answer to. (or God if that is your belief).