On Wednesday, Nancy Pelosi declared that Congress should immediately return to Washington for an up-or-down vote on President Obama's war on the Islamic State. This is a game-changer, since Pelosi has the power to make it happen.

Although she is only the minority leader of the House, the War Powers Act provides Pelosi the tools she needs [see section 5(a)] to move ahead. It explicitly gives a 30 percent minority of the House, together with 30 percent of the Senate, authority to insist that the president call a special session of Congress to pass judgment on his new military intervention.

Recent congressional actions suggest that there is the requisite support for a Pelosi initiative. In mid-September, Congress granted itself a two month recess to go electioneering. But before leaving town, the House considered a bill authorizing President Obama to provide training for moderate Syrian rebels in Saudi Arabia. This was a modest bill, which made it clear that it didn't authorize the use of force by the American military. Nevertheless, it only passed by a margin of 273 to 156, with a bipartisan group of dissenters fearing that it was the first step down the slippery slope to war. Since only 131 House votes are required to pass the 30 percent threshold specified by the War Powers Act, Pelosi will be fishing in a large pool if she puts her brave words into action and undertakes a campaign for a special session.

When the House bill reached the Senate, it was attached as a rider to a larger measure funding the government through December 11. This meant that opponents of the Syrian operation could vote No only at the cost of risking a government shut-down. Nevertheless, 22 Senators -- ranging from Rand Paul to Elizabeth Warren -- took a stand against the bill.

Even more would sign a petition for a special session, since this stand-alone measure would have less dire consequences. All it would require is that Senators suspend electioneering for a few days to confront their constitutional responsibility to decide on questions of war and peace.

The War Powers Act of 1973 seeks to fulfill the "intent of the framers of the Constitution ... and insure that the collective judgment of both the Congress and the President" will govern the use of military force. While it allows the president to begin "hostilities" unilaterally, it requires him to gain Congressional consent within sixty days, and to terminate his initiative thirty days later if he fails. President Obama started this clock running when he formally notified Congress of his bombing campaign on August 8.

Since the clock is running out, Congress couldn't realistically reach a final decision by the October 7th deadline. But it could readily come to a vote by the November 6th termination date, and thereby allow the country to avoid a looming constitutional crisis. If nothing is done, the Supreme Court will be obliged to consider a legal challenge to President Obama's efforts to continue bombing after November 6th -- leading to a serious inter-branch confrontation.

The president claims that, despite the provisions of the War Powers Act, his continuing attacks on ISIS have an alternative foundation. On his view, President Bush did all the necessary work a decade ago when he convinced Congress to approve his wars against Al Qaeda and Saddam Hussein. Obama asserts that the language of the Bush-era authorizations is sufficiently broad to support his new war against the Islamic State.

This legal claim has been vigorously criticized by constitutional scholars across the political spectrum. But neither the Justice Department nor the White House Counsel has backed up Obama's bare assertion with a serious legal opinion.

On November 7th, however, members of the armed forces will have the right to test the president's claims in court. Since they have a personal interest in determining whether they are fighting an illegal war, they will satisfy the traditional test for legal standing -- forcing the Administration to stop stonewalling and engage in sustained legal argument in defense of its much-criticized positions.

Perhaps the Supreme Court will back the Administration when the case reaches its docket; perhaps not. But in the meantime, the escalating constitutional debate will erode the legitimacy of the president's leadership, and encourage Congressional second-guessing when his campaign encounters set-backs.

Rather than passing the buck to the courts, it would be far better for Pelosi to use her formidable political skills to lead Congress to engage in a deliberate and democratic decision on the wisdom of Obama's bombing campaign.

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Bruce Ackerman is a professor of law and political science at Yale and the author of the Decline and Fall of the American Republic .