Trump doesn't need Congress to strike in Syria

But what about the congressional power to declare war? Scholars nowadays are sharply divided over whether the Framers intended it as a check on the executive’s “independent” warmaking authority. Certainly at the time of the founding, the use of a formal declaration of war had fallen into desuetude. Yes, there is a reasonable case to be made that the Framers did indeed hope to restrict presidential use of the military without congressional assent. (That’s one reason for the early resistance to a standing army.) But the new nation did not behave as though a declaration was necessary. (Abraham Lincoln’s famous aphorism that the country should never go to war through the will of one man was a response to President James Polk’s invasion of Mexico somewhat in advance of congressional permission.)

Even 19th- and early 20th-century thinkers who considered a declaration of war to be important did not argue that it was constitutionally required. The reason a declaration should be made, wrote the prominent lawyer Daniel Chauncey Brewer in the 1890s, was that without it “neither enemies, friends, nor neutrals can be properly forewarned.” The function of a declaration of war, wrote Yale’s Simeon Baldwin as World War I erupted, was to create or announce the “legal condition of things.”