Authorizing the Use of Force Against ISIS: How to Define “Associated Forces”

Several congressional proposals for the authorization of the use of military force (AUMF) against ISIS have included authorization to target not just ISIS but also “associated forces” of ISIS.

The Obama Administration developed the theory of associated forces to expand the reach of the 2001 AUMF without going back to Congress for approval to fight new groups. The concept of associated forces does not appear in the 2001 AUMF itself. That law authorized force only against those who attacked the United States on 9/11 and those who harbored them—namely al Qaeda and the Taliban. By stretching the 2001 AUMF to apply to associated forces, the Obama administration used it to justify operations around the world against over half a dozen organizations, including groups that did not exist on 9/11.

National security law experts across the aisle agree that if an AUMF authorizes force not just against a specifically named group but also against associated forces associated of that group then, it should include a definition of that term. They also agree that the definition of associated forces should only include those groups who can legally be targeted under the laws of war: groups who are parties to the armed conflict against the United States. Clearly specifying the enemy is the height of democratic responsibility. It helps prevent mission creep and to ensure that the executive branch cannot interpret any new AUMF beyond what Congress authorized.