Yes, declarations of war are still relevant
According to the Washington Post, “[m]ost legal scholars find a war declaration irrelevant.” Maybe, but I’m not one of them as I explain in a just-published article in Harvard Law’s National Security Journal (“Why declarations of war matter”).
True, declarations of war are, for a variety of reasons, little used in the modern context – even though the U.S., for example, has involved itself in a number of major military engagements since World War II. But there are lots of things that are very rarely used but can have enormous implications if they ever were employed (think about nuclear weapons).
And reference to war declarations still arises from time to time. Consider that in 1989 President George H. W. Bush cited Manuel Noriega’s declaration of war against the United States as one of the reasons he decided to use force against Panama. In 1996 Osama’ bin Laden issued his “Declaration of War Against the Americans Occupying the Land of the Two Holy Places” and proceeded with a conflict that continues to this day. More recently, press reports say Russia “discussed declaring war” after Turkey shot down a Russian jet last year. This past July, North Korea called new U.S. sanctions “a declaration of war.”
I believe declarations of war still retain intrinsic legal and – especially – political vitality. In fact, at July’s Aspen Security Forum Representative Adam Schiff categorized “the failure for Congress to live up to its responsibility of declaring war or not declaring war” with respect to America’s current conflict against terrorist organizations as its biggest failure of recent years because it set a “terrible precedent by letting this war go on without any real debate over it.”
Anyway, if you are interested in reading more, here’s the link to the short essay.