ABSTRACT
The Martens clause was invoked mainly in response to assertions that the Nuremberg Charter, as applied by the tribunals, constituted retroactive penal legislation. The Martens clause does not allow one to build castles of sand. Except in extreme cases, its references to principles of humanity and dictates of public conscience cannot, alone, delegitimize weapons and methods of war, especially in contested cases. Thus, the Security Council invoked them outside the context of an armed conflict, to condemn the use of weapons against civil aircraft in flight. The advisory opinion and pleadings in the Nuclear Weapons case provide a useful frame of discussion for analyzing and interpreting the Martens clause. The terms of the Martens Clause themselves make it necessary to point to a rule of customary international law which might outlaw the use of nuclear weapons. The Court found that the Martens clause was an expression of preexisting customary law and that its "continuing existence and applicability" were beyond doubt.
