This is precisely the kind of “undeclared presidential war” that the Resolution aimed to prevent. As Obama’s war moved into its third year, it has generated powerful dissent on Capitol Hill. Its break with the law has led constitutionalists to cross party lines, uniting leaders of the right, left, and center to condemn Obama’s failure to seek Congress’s approval. In the words of Tim Kaine, the senator and Democratic vice-presidential candidate, the war with the Islamic State has “shown to all that neither the Congress nor the president feels obliged to follow the 1973 War Powers Resolution which would cause the president to cease any unilateral military action within 90 days unless Congress votes to approve it.”

But representatives on Capitol Hill can’t go to court to ask the judges to insist that the president follow the law. Under the U.S. Constitution, courts can’t resolve abstract debates between politicians. They only are there to decide concrete “cases and controversies” generated when illegalities do concrete harm to real people.

Here is where Captain Nathan Smith enters into the story. A career officer in the Army, he was ordered to serve a year’s tour of duty in Kuwait at the command headquarters of Operation Inherent Resolve charged with coordinating Obama’s war against ISIS. As an intelligence officer, he was under orders to locate the best sites for military intervention in the ongoing struggle.

Smith believes they violate the express terms of the 1973 statute. Given his oath to “support and defend the Constitution,“ he also believes that he is under an obligation to disobey the illegal orders of his commander in chief when they violate the Resolution and the Constitution. If he follows his oath and disobeys orders, he faces the prospect of a court martial and serious punishment.

To escape this dilemma, Smith filed a lawsuit in federal court in the District of Columbia to get a clear answer on the status of the president’s orders. I am serving as a constitutional consultant in the on-going litigation; my 2015 Atlantic article about the war on ISIS and the War Powers Resolution led Smith to file his lawsuit. Last Thursday, we filed a brief emphasizing the dangers involved in the way the Justice Department has responded to Smith’s lawsuit.

The government is trying to persuade District Judge Caroline Kollar-Kotelly that she should refuse to consider the merits of Smith’s case. It asserts that the Captain lacks the personal stake required to challenge the legality of the war—and ignores the fact that he potentially faces a court-martial if he is obliged to act on his considered legal judgments. Smith is not a conscientious objector. He is a deeply committed career officer who wants to serve his country in the war against ISIS—so long as it is consistent with his oath to “support and defend” the Constitution.