The President does not have power under the Constitution to unilaterally authorize a military attack in a situation that does not involve stopping an actual or imminent threat to the nation. In instances of self-defense, the President would be within his constitutional authority to act before advising Congress or seeking its consent. History has shown us time and again, however, that military action is most successful when it is authorized and supported by the Legislative branch. It is always preferable to have the informed consent of Congress prior to any military action. — 2007

My Take –  I agree with what he said in 2007.  Congress declares war.  The executive branch prosecutes wars, but it has to get an OK from the people’s representatives before it does so.   Apparently going to Congress over Libya wasn’t necessary, no matter how necessary it was before the President was elected.  By sneering at those who called him on it, the President spit upon over 200 years of tradition and good practice, including during times of national emergency, such as after Pearl Harbor and 9/11.  I just hope that Libya was an aberration, and not a portent of what we can expect in the future.  When a national leader has unfettered power to instigate wars, without even the rubber stamp of getting approval from the legislature, nothing will stop them from using and abusing that new power.