Late Tuesday night, the House forced Washington to confront a question it has spent decades avoiding: who owns an American war?

On September 15, the House voted 220-204 for H. Con. Res. 93, directing President Trump, under Section 5(c) of the War Powers Resolution, to remove U.S. forces from hostilities against Iran unless Congress authorizes their continued use. Democrats voted 213-0 for it. Republicans voted 203-7 against it.

That partisan split is not the story.

That pattern is hardly unique to Trump. Members of Congress have often interpreted presidential war powers more generously when the president belongs to their own party and more narrowly when he does not. The tendency reaches far back in American history. Yet partisan lines sometimes break: libertarian Republicans have joined progressive Democrats to restrain presidential war-making, as last year’s Massie-Khanna coalition on Iran demonstrated.

Set party aside. The constitutional problem would remain if a Democrat sat in the Oval Office and Republicans controlled Congress.

The United States has been engaged in hostilities with Iran since February 28. What began as Operation Epic Fury has now entered its seventh month.

This is no longer a question about a president responding to an emergency.

The administration has described objectives that go well beyond that: destroying Iran’s ballistic-missile production, crippling its navy, severing support to terrorist proxies, preventing a nuclear weapon, and limiting Iran’s ability to project power beyond its borders. The White House has also treated American control of the Strait of Hormuz and protection of shipping through it as a continuing strategic objective.

Those goals can be judged on their merits. Constitutionally, they raise a different question than whether a president may order forces to defend themselves against an imminent attack.

At what point does defending the nation become the nation’s sustained prosecution of a war?

The Constitution does not answer that cleanly. Article II makes the president commander in chief. Article I gives Congress the power to declare war and to raise, fund, and regulate the armed forces. The branches have disputed that boundary since the founding.

The 1973 War Powers Resolution tried to impose order on that dispute. Congress declared that presidential introduction of U.S. forces into hostilities should rest on a declaration of war, specific statutory authorization, or a national emergency created by an attack on the United States, its territories, or its armed forces.

H. Con. Res. 93 invokes one of that law’s mechanisms. It directs withdrawal from hostilities against Iran unless Congress authorizes them, while preserving forces needed to defend the United States, an ally, or a partner from imminent attack.

That distinction matters. Congress can contest an open-ended offensive campaign without denying the president authority to protect servicemembers from an incoming missile.

Here is the paradox. H. Con. Res. 93 relies on Section 5(c) of the War Powers Resolution, which lets Congress direct withdrawal through a concurrent resolution, a resolution that passes both chambers but never reaches the president’s desk for signature or veto.

In 1983, the Supreme Court decided INS v. Chadha, striking down a one-house legislative veto that bypassed the Constitution’s bicameral-passage and presentment requirements. The court did not specifically strike down Section 5(c). But the Congressional Research Service concludes that the constitutional validity of its concurrent-resolution mechanism is doubtful in Chadha’s wake.

Congress is trying to challenge the president’s war-making authority by relying on a congressional mechanism whose own constitutionality is in doubt.

Congress confronted that problem after Chadha by establishing another path: expedited consideration of a bill or joint resolution directing the removal of forces. Such legislation would go to the president for signature or veto. Yet Congress also preserved Section 5(c)’s concurrent-resolution procedure despite its apparent constitutional defect.

Congress also has a clearer tool: specific statutory authorization for military force. Congress has not formally declared war since World War II. Instead, statutory authorizations have become its predominant means of approving hostilities, including the Vietnam-era Gulf of Tonkin Resolution, the 1991 Persian Gulf authorization, the post-9/11 AUMF, and the 2002 Iraq authorization.

An Iran AUMF would force both branches to answer questions the current standoff leaves open. What is the United States trying to accomplish? Prevent an Iranian nuclear weapon? Destroy Iran’s capacity to rebuild its missile forces? Protect American troops and allies? Keep the Strait of Hormuz open? Stop Iran from again arming proxies across the region? And the harder question: how long does that authority last, and what marks its end?

Those are not operational details. They define the constitutional shape and duration of American military power.

There is a moral dimension too. As someone who once wore this country’s uniform, I take seriously what the Christian Just War tradition calls legitimate authority, one of the traditional criteria for judging whether resort to war is morally justified. That test matters more, not less, once a limited strike hardens into a prolonged campaign. Who holds lawful authority to wage war is not a technicality when American troops are risking their lives and people are dying on the battlefield.

Which returns the debate to its center. The president is commander in chief. Congress holds war powers of its own. Presidents of both parties have used force without prior authorization, and Congresses of both parties have struggled to defend their own prerogatives, as the Council on Foreign Relations has documented. Iran now exposes the price of that decades-long drift.

The question that matters is not whether Democrats beat Republicans on Tuesday’s vote, or even whether Iran remains dangerous. It is this: when an emergency becomes a campaign, and a campaign becomes a prolonged war pursuing broad national goals, which branch bears constitutional responsibility for it?

H. Con. Res. 93 has put that constitutional question squarely before the country. The disputed mechanism Congress chose to employ only makes the problem more revealing.

Seven months into the Iran conflict, the issue is no longer theoretical. It is the constitutional question at the center of this war: Who owns it?