Let’s be clear: Syria’s Bashar Assad is a bum and probably a war criminal. Yet it does not follow that the president of the United States possesses the authority to order an armed attack on the sovereign state that Assad governs. 

That authority rests with the Congress, as Article I, Section 8 of the Constitution explicitly states. As a result of President Trump’s actions, that provision has now become a dead letter. The last constraints inhibiting the use of force by whoever happens to be commander-in-chief have now disappeared. When it comes to initiating hostilities, the occupant of the Oval Office is now omnipotent.

Granted, presidents have been encroaching on congressional war powers for decades now. At least since Harry Truman ordered US troops into Korea back in 1950, the role allotted Congress in authorizing the use of force has eroded. Not since December 1941 has Congress actually “declared” war, now a quaint notion akin to asking your girlfriend’s dad for her hand in marriage. 

True, to sustain a pretense of relevance, Congress has periodically issued broad statements that essentially give presidents a free hand to do as they see fit. The Tonkin Gulf Resolution of 1964 offers one infamous example of this practice. The so-called Authorization to Use Military Force, or AUMF, passed with minimal debate on September 14, 2001, offers a second.

That document directs the president to “use all necessary and appropriate force against those nations, organizations, or persons he determines planned, authorized, committed, or aided” the events of 9/11. In effect, it says to the president: You decide; just keep us safe. ...