Update: 9:30 a.m. ET Wednesday

President Obama has sent Congress proposed legislative language that would grant him specific permission to make war on the group calling itself the Islamic State.

If approved by the House and Senate, that language will formalize the struggle against the Sunni extremists who are also known as ISIS or ISIL — and are best known for such actions as the torture killing of a captive Jordanian pilot and the beheading of other hostages from around the world.

The anti-ISIS struggle has already been underway for six months, with Obama ordering airstrikes against thousands of ISIS targets and supplying military aid to anti-ISIS forces in Iraq and Syria.

Why has the president not sought formal permission for any of this up to now? Why has Congress not focused on a firm insistence that he do so?

The answers are both legal and political. The White House cited previous OKs from Congress in the region, and for a time no one wanted to elevate the ISIS threat, or seem unprepared to deal with it. Both parties were also dealing with the complex calculus of November's midterm elections.

The Obama administration also might have preferred not to have its actions framed by a formal Authorization for Use of Military Force (AUMF). This was, after all, the instrument by which previous wars in the region were prosecuted by the Bush administrations — both of them with the approval of Congress in 1991, 2001 and 2002.

Surely it is not a welcome thought for the current White House that its moves in the Islamic world will now be accompanied by the phrase " ... just like President Bush."

But the ISIS crisis has deepened, becoming the salient challenge posed by radical Islam in all its forms at this moment in time. The torture and beheadings and terrorist attacks in Paris blur into a single provocation — even when they are carried out by unconnected cells of militant Islamist radicals. A heightened period of military engagement is coming, and a clearer legal justification is needed for what will come next.

So how should the commander in chief be governed in pursuing this new war? We no longer contemplate outright declarations of war. In the nuclear age, and in the era of asymmetrical wars between great powers and guerrilla movements, war has long since been redefined. Beginning with the Korean conflict of the early 1950s, the U.S. has made war by other names — including "police action" and "peacekeeping." The Vietnam War dragged on for a decade under the congressional authority of the open-ended 1964 Gulf of Tonkin Resolution.

In more recent decades, the superannuated declaration of war has been superseded by the sleek and facilitating AUMF.

An AUMF was approved by Congress in January 1991, responding to a request from President George H.W. Bush. The provocation was Iraqi dictator Saddam Hussein's invasion of his oil-rich neighbor, Kuwait, on the Persian Gulf. The first President Bush wanted to send something like 250,000 troops to liberate Kuwait, and he had lined up the support of dozens of other countries — many of them Arab or Islamic.

Congress was restive at first, complaining and hectoring throughout the fall of 1990 (another midterm election year). But as the troop buildup in the Gulf continued, the leaders of the Democratic majorities in the House and Senate insisted on a showdown with the president.

Days of reasonably serious and substantive debate ensued in both chambers, and in the end Bush got his AUMF. The vote in the Senate was a stunningly close 52-47. The House was more easily persuaded, approving 250-183.

The result was then known as the Persian Gulf War, an immediate victory for the U.S. and its allies. The Iraqi army was expelled from Kuwait with heavy casualties. But President Bush decided to settle for the basic objective and ended the hostilities with much of the Iraqi military and political power structure still intact. Saddam Hussein had lost his prize but retained his pride, claiming he had fought the U.S. to a standstill.

The second AUMF was associated with the second President Bush. It was approved by Congress in 2001 just one week after the attacks of Sept. 11, 2001. At the time, the House was controlled by Republicans, most of them eager to grant the second Bush extraordinary powers to pursue the perpetrators of the attacks and terrorism in general.

The Senate, narrowly controlled by Democrats, had more misgivings about a blanket authority. Some senior senators remembered their regrets from the Gulf of Tonkin tragedy. In the end, however, that chamber went along as well.

A year later, after a far more spirited debate, the Congress approved a new AUMF directed at the regime of Saddam Hussein. Although no link between Baghdad and the Sept. 11 plotters was ever proven (nor even explicitly alleged), the second Bush administration was committed to revisiting the unfinished business of the first. It was enough that Saddam Hussein had rejoiced in the success of the Sept. 11 attacks, and that he had supposedly defied the world community by pursuing "weapons of mass destruction."

No such weapons were found after the AUMF of that fall was used to justify an invasion of Iraq in March 2003. But the U.S. forces once again easily vanquished the official military of Iraq, this time marching on to Baghdad and eventually capturing Hussein himself hiding in a "spider hole."

There followed, however, years of insurrection and sectarian warfare in Iraq, amid floundering efforts to establish a pluralistic government. That effort continues today, and its travails have left the countryside vulnerable to ISIS — among other sorrows.

Each of these AUMF votes has proven politically contentious in some measure. The 1991 votes reflected the misgivings left over from Vietnam. The 2001 vote, along with the Patriot Act, ushered in the war on terror that would dominate American foreign policy for a decade and more.

And a yes vote on the 2002 AUMF, which seemed quite mainstream at the time, would come back five years later to haunt the presidential candidacy of then-New York Sen. Hillary Clinton. Without that pro-war vote, and all the sorrows that followed on that invasion, there would have been far less daylight in 2007 and 2008 for Clinton's upstart challenger, Illinois Sen. Barack Obama.

Unintended consequences, in both the international arena and the realm of domestic politics, have followed upon each of these AUMF votes. They are, in many ways, the most remembered legacy of the two Bush presidencies.

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