International Norms and How They Work
How unwritten rules of behavior govern state conduct — from diplomatic immunity to the taboo against chemical weapons.
What Are International Norms?
International norms are shared expectations about appropriate behavior for states. Some are codified in treaties — the Geneva Conventions define norms for the treatment of prisoners of war. Others are unwritten but powerful — the taboo against the use of nuclear weapons has held since 1945 despite no formal treaty banning their use (until the 2017 Treaty on the Prohibition of Nuclear Weapons, which nuclear-armed states have not joined).
Norms matter because they constrain behavior even in the absence of enforcement. States that violate widely accepted norms face reputational costs, diplomatic isolation, and sometimes economic sanctions. Russia's annexation of Crimea in 2014 violated the post-World War II norm against territorial conquest by force. The near-universal condemnation and sanctions that followed — even if insufficient to reverse the annexation — demonstrated the norm's continuing power.