Update: 'Smith v. Obama': A Servicemember's Legal Challenge to the Campaign Against the Islamic State [April 4, 2017] [open pdf - 154KB]
From the Summary: "On November 21, 2016, a United States district court dismissed a lawsuit by a U.S. Army intelligence officer, Captain Nathan Smith, challenging the Obama Administration's legal authority to conduct the military campaign against the Islamic State. Although the court dismissed the complaint on jurisdictional grounds (discussed below) without reaching the merits of the challenge to the President's authority, the case serves to highlight several ongoing issues related to Congress's role in the ongoing military actions against the Islamic State, dubbed Operation Inherent Resolve. As outlined in earlier CRS [Congressional Research Service] Reports, the Constitution allocates the power to carry out military operations to both the executive and legislative branches, but the breadth of Congress's role in military operations has been the subject of longstanding debate. Captain Smith argued that Operation Inherent Resolve exceeds the President's commander-in-chief authority under Article II of the Constitution and the two existing statutory authorizations for the use of military force (AUMFs): the 2001 AUMF enacted in aftermath of the September 11, 2001 and the 2002 AUMF against Iraq."
CRS Legal Sidebar, April 4, 2017
Federation of American Scientists: http://www.fas.org/sgp/crs/index.html