In customary international law, the obligation to cooperate in good faith and to settle disputes by peaceful means is an example of what?

• A. Treaty law
• B. Domestic policy
• C. A customary norm arising from consistent state practice and opinio juris
• D. A Security Council prerogative

Answer: (C)

This question tests how customary international law is formed: a rule must be upheld by states as general practice and be believed to be legally obligatory (opinio juris). The obligation to cooperate in good faith and to settle disputes peacefully fits that pattern because states routinely engage in negotiations, mediation, arbitration, or other peaceful means, and they generally view such conduct as something they are legally bound to do, not just politically advantageous. Over time this combination—repeated practice plus the belief that it is legally required—creates a customary norm that governs state behavior independently of any specific treaty. It isn’t merely domestic policy, which operates within a country’s borders, nor is it a prerogative of the Security Council, which concerns decisions of an international body rather than a general obligation binding states as customary law.