Ever since George W. Bush in 2002 began driving up public frenzy for his invasion of Iraq on trumped-up justifications a year later, Congress's constitutional role to declare war has continued to be cold-shouldered.
Then, Mr. Bush relied on an interpretation of Article II, Section 2 — specifying that "the President shall be Commander in Chief of the Army and Navy ... when called into actual Service of the United States" — to start that war. Under the inventive mind of his Justice Department legal counsel, conservative lawyer John Yoo, the notion of "the unitary executive" held sway, giving the president sole power to launch armed conflict.
Mr. Yoo, a deputy assistant attorney general at the time, argued in April 2002 before a Senate subcommittee that the president thereby had "the constitutional authority to introduce U.S. armed forces into hostilities when appropriate, with or without specific congressional authorization."
With a nice touch of bureaucratic condescension, Mr. Yoo added at the end that the Bush administration had "independent authority [to wage war] under the Constitution, but we would be willing to act with congressional support." The subcommittee chairman, Sen. Russell Feingold, and an array of constitutional scholars he had summoned to the hearing, emphatically said otherwise.
One Georgetown law professor, Jane E. Stromseth, cited James Madison in 1793, declaring: "In no part of the Constitution is more wisdom to be found than in the clause which confides the question of war or peace to the legislature and not to the executive department."
But Mr. Bush went ahead in his merry if misguided way, building up the invasion force that tumbled Iraqi dictator Saddam Hussein in 2003 and left chaos and a political and societal mess behind in Iraq, which has struggled to survive since that day.
President Barack Obama has not relied on that "unitary executive" theory to justify his campaign to "degrade and ultimately destroy" the new Islamic State, which has carved out parts of northern Iraq and Syria with a reign of terror that now imperils the Middle East, and by extension U.S. national security.
Instead, his lawyers say for now he is using Mr. Bush's 2002 authorization of use of military force, though Mr. Obama says he doesn't need it and is for its repeal. But he has been dragging his heels on proposing a replacement. Meanwhile, there's a certain irony in continuing to cite Mr. Bush's 12-year-old basis for the disastrous Iraq invasion that Mr. Obama himself has declared a "dumb war" and from which he has labored to extricate this country ever since he entered the Oval Office.
Not waiting for a presidential decision on a new war authorization, several members of Congress have taken tentative steps to restore the legislative branch's role in deciding this latest war-making issue. Democratic Sen. Robert Menendez, the outgoing committee chairman, and 2016 Republican presidential hopeful Sen. Rand Paul have called for a three-year authorization for the president to use "necessary and appropriate" force against the Islamic State, but without use of American troops in "ground combat operations."
Earlier, Democratic Sen. Tim Kaine called for the air strikes already underway but for one year only. Mr. Obama himself has said he expected the threat from the Islamic State to last longer than that, suggesting it would go on after he leaves office in January 2017.
The president's failure so far to give Congress a clear indication of his strategy in this latest undeclared war has only added to the growing public impression of the uncertain trumpet he is sounding on foreign policy. Republican Sen. John McCain particularly has lamented Mr. Obama's flat restriction of "boots on the ground" in the latest armed challenge.
A Washington Post report of still more U.S. forces to Afghanistan, where their withdrawal had been scheduled for the end of 2015, casts further doubt on whether Mr. Obama's determination to get Uncle Sam out of the war business can come close to achievement by the end of his presidency.
Jules Witcover is a syndicated columnist and former long-time writer for The Baltimore Sun. His latest book is "Joe Biden: A Life of Trial and Redemption" (William Morrow). His email is firstname.lastname@example.org.