There's a lot of fussing and fuming over the White House report to Congress on the Libya operations -- and most of it is misdirected. The real issue isn't a legal question, it's a policy and political question: will Congress express its collective judgment on Libya or just play political games?
The White House paper on Libya is actually a reasonable response to Speaker Boehner's lengthy list of questions -- the same sort of information made available in the ten hearings and 30 briefings on Libya documented by the Administration. Now it's up to Congress to take action. The paper argues that the United States is not involved in "hostilities" because U.S. forces are largely in a support role.
What do you expect White House lawyers to say? For four decades, they all have argued that the President doesn't have to comply with the War Powers Act. Even eminent scholars like Harold Koh found ways to "stand where they sit" in the Executive Branch.
The purpose of the War Powers Act was to prevent, or at least limit, presidential warmaking. The actual language, of course, allows it for 60 days. But in practice, every major military operation not authorized by Congress [as was done for Lebanon, the Gulf War, Afghanistan, and Iraq] has been limited both in scope and duration, usually to under four months. So regardless of the legalities, the law has had the intended beneficial result. In the case of Libya, it sure looks as if the lawyers -- as well as Sec. Gates and the military leaders -- weighed in to keep the US role limited.
As President Obama said in reporting, as required by the law, the deployment of US forces against Libya, it's time for the Congress to express its will. Regrettably, Congresses of both parties have regularly evaded their responsibilities over the decades by failing to pass legislation, either to authorize or limit or halt the ongoing military operations. Lawmakers have the power of the purse. They also can impose goals and conditions for the operation -- as they have done in past conflicts. [Be one of the few in the world to have read my book on this, Congress at War.]
It doesn't matter what the lawyers say about this. What matters is what the lawmakers do. And if that means finding majorities for something less than the most extreme positions, tough; that's the legislative process.