The Article II “Humanitarian Intervention” War Power
Assuming there really was authorization from the Iraqi government, I don't have any doubt that the U.S. has the right under the international law to launch new airstrikes in Iraq. But the domestic authority for the U.S. airstrikes is much more murky, and, as Ilya Somin argues here, Congress might need to authorize continuing military action. Jack Goldsmith goes through the domestic legal bases...