The Martens Clause first appeared in the preamble to the 1899 Hague Convention II, and was subsequently reiterated by both Geneva Conventions of 1949. In Additional Protocol I (1977) it was promoted from preamble to provision:
‘civilians and combatants remain under the protection and authority of the principles of international law derived from established custom, from the principles of humanity and from the dictates of public conscience’ (art 1(2))
Perspectives on the ICRC Study on Customary International Humanitarian Law by