Here is a copy of the memo produced by the Office of Legal Counsel which justified the firing of missiles to protect the residents of Benghazi in 2011.The involvement of Congress hinged on the definition of "war."
. . . in 2011, the administration took military action in Libya without any congressional approval, prompting the Republican-led House of Representatives to vote to rebuke the president.
In its legal justification for action in Libya, the Justice Department's Office of Legal Counsel (OLC) argued that Congress' authority to declare "war" was limited by the definition of war. "This standard generally will be satisfied only by prolonged and substantial military engagements, typically involving exposure of U.S. military personnel to significant risk over a substantial period," the OLC wrote.
The OLC augmented that argument by noting the operation in Libya would be limited to air strikes in support of a United Nations resolution, and that no American lives would be put at risk. And while Mr. Obama in 2007 said the president could only act unilaterally in a matter of self-defense, the OLC in 2011 justified the use of force in Libya as "in the national interest."
The story notes that there has been no UN support for the strikes, which makes this different than Libya.
