"Two separate but closely related issues confront Congress each time the President introduces Armed Forces into a situation abroad that conceivably could lead to their involvement in hostilities. One issue concerns the division of war powers between the President and Congress, whether the use of Armed Forces falls within the purview of the congressional power to declare war and the War Powers Resolution (WPR). The other issue is whether or not Congress concurs in the wisdom of the action. This report does not deal with the substantive merits of using Armed Forces in specific cases, but rather with congressional authorization for military action, and the application and effectiveness of the WPR. The purpose of the WPR (P.L. 93-148, passed over President Nixon's veto on November 7, 1973) is to ensure that Congress and the President share in making decisions that may get the United States involved in hostilities. Compliance becomes an issue whenever the President introduces U.S. forces abroad in situations that might be construed as hostilities or imminent hostilities. Criteria for compliance include prior consultation with Congress, fulfillment of the reporting requirements, and congressional authorization. […] Most recently, issues associated with presidential compliance with the War Powers Resolution have arisen over his use of U.S. military forces to support a U.N. sanctioned 'no-fly zone' in Libya, without obtaining congressional authorization for such action. Debate continues on whether using the War Powers Resolution is effective as a means of assuring congressional participation in decisions that might get the United States involved in a significant military conflict. Proposals have been made to modify or repeal the resolution. None have been enacted to date. This report will be updated as events warrant."
CRS Report for Congress, RL33532