On a voyage he saw with his clairvoyance that a man aboard the ship planned to sink the ship and kill all the crew and passengers. He could find no other way to stop the man, and so, out of compassion for the future suffering this man would incur through his actions, so he killed him to prevent the man's karmic suffering.
So, it can be done in a karmically clean way, but the intention must be completely pure. This degree of purity is hard to attain, but maybe some Buddhists can do so in this situation.
Just try to explain THAT in a court of law!
great parable , thanks