Youngstown and Declarations of War

The United States has not formally declared war since 1942. We've issued some functional war declarations against Iraq and Al Qaeda. There have been other military actions that arguably did not require a formal declaration. But there have been major wars (think Korea and Vietnam) that in an earlier era probably would have triggered war declarations. Why have none occurred since WWII?

One answer is that Youngstown gave President Truman a pass on that issue. The Court could have said that he lacked the power to seize the steel mills on military necessity grounds because no declaration of war was issued. The Solicitor General was asked about this at oral argument, and Justice Jackson flirted with this argument in a draft of his concurrence. In the end, though, Jackson said that he did not need to address that issue to reach his judgment that Truman's action was unlawful.

Perhaps this was a mistake. The OLC most often cites Jackson's concurring opinion for the proposition that the President has broad latitude to use troops abroad even in the absence of a war declaration. Given that statement, why should Presidents bother to seek a declaration? And none have. Truman's reasoning was that seeking a formal declaration of war for Korea would weaken the nuclear deterrent. That was a hard argument to resist in 1952, but experience suggests that the price was too high.