necessity

• where they acted to prevent a greater evil from happening, such as in medical procedures
• RE A (Conjoined Twins)


  sets the test requires

  1. the act to be necessary to avoid inevitable evil
  2. no more was done than necessary
  3. the evil inflicted was not disproportionate to the evil avoided
• Dudley and Stephens


  not a defence to murder
• RE F (Mental patient sterilisation)


  can be used to sterilise those with severe mental disabilities without consent
• R v Quayle


  cannot be used for cannabis (pain relief)