Constitutional FAQ Answer #136
Q136. "Can the US declare war in order to free the people of the country? I heard this once but I don't know if its true, or if it was what document did it came out of."
A. The Congress is given the power to declare war. There is no limitation or condition on this power. The Congress can declare war at any time for any reason it wishes, including to free the people of a country from oppression, or because we dislike the color of the other nation's flag. The trick is that Congress as a body must agree by at least a majority, and that is why declarations of war are so rare. It is a major task to convince half of both houses of Congress that a declaration of war is necessary.