(C) Kapok Tree Diplomacy. 2011. All rights reserved. Jeff Dwiggins. FREE CONTENT
Customary international law (IL) derives from a “combination of ‘state practice’ and opinio juris, the belief that a certain type of conduct under IL is an obligation (Byers 4). According to Byers, new rules require “widespread support” before they become part of customary IL (4). Cerone adds that the Martens Clause of the Hague Conventions binds 
“belligerents to remain under the protection and the rule of the principles of the law of nations” until such time as custom becomes statutory in some form or fashion (qtd. in Mertus & Helsing 219-220). Thus, custom serves as a “gap-filling” measure that universally binds all states and may apply to scenarios where IL has not yet been formalized into statutes (Mertus & Helsing 220). Read more
