A federal appeals court is weighing on a rare and expedited basis a lawsuit challenging the president's right to wage war on Iraq without a formal declaration of war by Congress.

Filed by a dozen dovish House Democrats, three anonymous soldiers and 15 parents of soldiers, the lawsuit before the U.S. Court of Appeals for the 1st Circuit, in Boston, argues that Congress has ducked its responsibilities and delegated its war-making powers to the president. Congress voted in October to give President Bush the power to attack if Iraq failed to comply with U.N. mandates or if the president determined that Iraq presented a threat to the security of the nation.

Congress last issued a formal declaration of war in December 1941, against Japan and Germany.

A lower court judge last month dismissed this lawsuit almost out of hand, and few legal scholars expect the federal appeals court to block a president on the cusp of war. But a three-judge appeals court panel has agreed to quickly take and hear the case. Lawyers expect a ruling in the next day or two.

John C. Bonifaz, the lawyer bringing the legal challenge, says that Congress cannot simply transfer its war-making powers to the president as a hedge against a future conflict. "If we're going to go to war now, we need a debate," he said. "If it strengthens the president's hand, so be it. At least people can be held accountable."

Senior Justice Department officials respond in court documents that war is, at its heart, a political question between the president and Congress, and that judicial intervention would be "highly inappropriate." They assert that a diplomatic solution is possible and that Congress, in any case, gave all the approval that is necessary in October.

Justice Department lawyers also assert a far more expansive presidential power: If he wants to, they argue, the president can wage war all on his own, without congressional approval. This, even among legal scholars sympathetic to Bush, is a deeply controversial interpretation.

"Hundreds of years of congressional action support the President's unilateral war making powers," the Justice Department states in its brief. The president is authorized "to unilaterally use military force in defense of the United States's national security interests."

Seventy-three constitutional law professors have signed on to Bonifaz's lawsuit. These professors, in legal papers, decry the "radical proposition" that the president can launch a "massive invasion" without the consent of Congress.

A federal court threw out in 1990 a similar challenge by 54 members of Congress against the impending Persian Gulf War. The judge ruled that while Congress had a right to declare war, the nation at that time was not yet at war.

The question of the president's war-making powers and the tension with the legislative branch over the issue have confounded politicians and scholars almost from the founding of the Republic. The United States has fought five legally declared wars.

By contrast, Deputy Assistant Attorney General Gregory Katsas told the appellate panel last week, U.S. forces have fought more than 100 times without a congressional declaration of war. Since World War II, the United States has intervened militarily in Korea, Vietnam, Haiti, Lebanon, Nicaragua and the Persian Gulf region.

"While you can talk about original intent, the war-making powers have been honored more often in the breach," said Robert Dallek, a professor of history at Boston University and author of a forthcoming book on John F. Kennedy. "It's not a dead letter, but it's been greatly modified by our experiences of the 20th century."

The plaintiffs in this case argue that the constitutional founders wanted to forestall a monarchical executive who might squander the treasury and thousands of young lives on war. By giving Congress the right to declare war, the plaintiffs argue, the Founding Fathers situated war-making powers in the most representative wing of government.

"The president cannot anoint himself king and simply declare war," Bonifaz said. "That goes to the heart of our Constitution."

But some prominent legal scholars say Bonifaz is flogging an outdated legal argument. At least since the Vietnam War era, federal courts have implicitly held that a formal declaration of war is not necessary. "There's nothing magic about a declaration of war," said Lori Damrosch, a professor of constitutional law at Columbia University law school. "As long as Congress expresses its approval, it can pick the means."

Michael J. Glennon, a professor at Tufts University Fletcher School of Law and Diplomacy, suggested that the courts should wade more aggressively into challenges to the executive war-making powers, but that this isn't the right case. "The debate was terrible last October," he said. "But these are political misjudgments, not constitutional violations."

Bonifaz and the plaintiffs, however, hold that theirs is an effort to return the United States to an earlier, and truer, constitutional interpretation. Their briefs note that scholars view the United States's Korean intervention as a "fatal moment" that threw the separation of war-making powers into disarray.

"This Court," Bonifaz's brief says, "should direct the district court to enjoin the defendants from launching a military invasion of Iraq absent a congressional declaration of war."

Lawyer John C. Bonifaz, with copy of U.S. Constitution, and plaintiff Charles Richardson announce the Feb. 13 filing of a war powers lawsuit. A federal appeals court has agreed to hear the case.