Lately there has been a major discussion about if the President of the United States has the power to declare war. To answer this question I have turned to early documents. The best one I have found is A Familiar Exposition of the Constitution of the United States: Containing a Brief Commentary On Every Clause, Explaining the True Nature, Reasons, … and General Readers. with an Appendix, Conta
Joseph Story was Justice of the Supreme Court from 1811 to 1845. He was born three years after the Declaration of Independence, and his father served in the American Revolution. So he is a most reliable source for information concerning the Constitution and Early American History. OK, so what does he say on the matter?
- Article I Section 8 of the Constitution clearly states that only Congress can declare war.
- Some argue that the President can declare war because he is the Commander and Chief of the Armed Forces. However Article II Section 2 states that the president becomes Commander And Chief when called into action (by Congress). Therefore the President is not granted the Power to declare war as per the Constitution
- You see, as Judge Napolitano points out, to grant the president the power to declare war would give him “King Like Powers”. This the Founding Fathers were adamantly against.
- Others argue that the War Powers Act grants the President the power to declare war. Justice Joseph Story (page 303 of his book) says it is the duty of the courts to declare any unconstitutional laws (such as the War Powers Act) Void.
In other words, the Constitution is the supreme law of the Land with treaties and laws subordinate to it. The Constitution can not be changed by a simple law, one must follow the legal procedures of amending the Constitution to do so.
To see the video series of Judge Napolitano explaining the Constitution click here.
Update: 
The U.S. Supreme Court ruled on June 16, 2011 that:
a court has no “prudential” license todecline to consider whether the statute under which the defendant has been charged lacks constitutional application to her conduct. And that is so even where the constitutional provision that would render the conviction void is directed at protecting a party not before the Court. ….
In short, a law “beyond the power of Congress,” for any reason, is “no law at all.” Nigro v. United States, 276 U. S. 332, 341 (1928). The validity of Bond’s conviction depends upon whether the Constitution permits Congress to enact §229. Her claim that it does not must be considered and decided on the merits.
(but here is an frequently overlooked, and highly significant part of this ruling) “The Court’s ruling today, in a tight opinion by Justice Kennedy, makes clear that individuals (not just States) can indeed raise Tenth Amendment claims that the federal government has overstepped its enumerated powers.”
