Why did Franklin D. Roosevelt have to address Congress first?

Answer 1

President Franklin D. Roosevelt addressed a joint session of Congress with the explicit intent of asking Congress to declare war on Japan after the Pearl Harbor attack. By the United States Constitution (Article One, Section Eight), only Congress has the authority to declare war on another nation, and the request must come from the President.

The request for a Declaration of War was also a joint broadcast to the U.S. as a nation; there was little debate on the matter, as emotions were running high after the attack. The issue wasn't just the unprovoked attack; the U.S. was incensed (to put it mildly) that the attack came during what it believed were peace negotiations in good faith between the U.S. and Japan.

The Japanese Government had issued instructions to its Ambassador to issue to the U.S. its formal notice of ending talks, as well as its formal declaration of war before the Pearl Harbor attacks began. However, delays in dealing with the radio transmission by the Japanese Embassy resulted in the attacks occurring an hour before the messages were formally delivered by the Japanese Ambassador to Secretary of State Cordell Hull. Delays were due to the message being transmitted in several separate parts to the Japanese Embassy in Washington, D.C., requiring decryption, translation, typing, and formal prep for diplomatic presentation.

The difference between Roosevelt asking for Declaration of War and other Presidents since then is a sticky Constitutional issue. While only Congress can declare war, the President, as Commander in Chief of the U.S. Armed Forces, has a Constitutional mandate to protect the country, and the Constitution gives the President flexibility to use military force without a formal declaration from Congress. Congress, after Vietnam, attempted to curtail Presidential power in this area by enacting the War Powers Act, which essentially says that the President needs Congressional approval before using military action. Since it's been enacted, Presidents have essentially ignored it, citing it as unconstitutional encroachment by the legislative branch over the executive branch's authority. To date, Congress has been unwilling to test the issue in court, an indication that they'd likely lose.

However, Presidents aren't stupid; they know they need Congressional support for military action as Congress controls the military budget, and you can't fight without money. Therefore, no military action taken by a President is taken without some support from Congress.