On March 24, 1999, NATO launched a 78-day air campaign against Yugoslavia without United Nations authorization, without a legal mandate, and with consequences nobody fully predicted. Legal scholars largely agree it violated international law. Humanitarian scholars largely argue it may have been necessary. And a post-war investigation found that the worst atrocities in Kosovo came after the bombs started falling, not before. It's a story where every side has a legitimate argument and where the exception NATO carved into international law in 1999 is still being used today by nations NATO never intended to empower.