Civil process and criminal procedure concern the principles that courts should observe as a trial and appeals proceed. In exceptional circumstances defences can apply to specific acts, corresponding to killing in self defence, or pleading insanity. Another instance is within the 19th-century English case of R v Dudley and Stephens, which tested a defence of “necessity”. Three crew members and Richard Parker, a 17-year-old cabin boy, had been stranded on a raft. They argued it was necessary to kill the cabin boy to protect their very own lives.
John Austin’s utilitarian reply was that law is “commands, backed by menace …