examples of crimes include murder, assault, fraud and theft. in exceptional circumstances defences can apply to specific acts, such as killing in self defence, or pleading insanity. another example is in the 19th-century english case of "r v dudley and stephens", which tested a defence of "necessity". the "mignonette", sailing from southampton to sydney, sank. three crew members and richard parker, a 17-year-old cabin boy, were stranded on a raft. they were starving and the cabin boy was close to death. driven to extreme hunger, the crew killed and ate the cabin boy. the crew survived and were rescued, but put on trial for murder. they argued it was necessary to kill the cabin boy to preserve their own lives. lord coleridge, expressing immense disapproval, ruled, "to preserve one's life is generally speaking a duty, but it may be the plainest and the highest duty to sacrifice it." the men were sentenced to hang, but public opinion was overwhelmingly supportive of the crew's right to preserve their own lives. in the end, the crown commuted their sentences to six months in jail.