THE RETURNING Congress cannot avoid being called on to address the Iraq crisis, which blew up while it was in recess and which is in a politically sensitive phase now. Almost everyone agrees that a president can dispatch forces for certain emergency or short-term purposes, as President Bush has done in the Persian Gulf. But now the question arises of whether and how Congress will insist that they cannot stay for any greater length of time without its approval. This is the mandate inscribed in law when Congress passed the War Powers Resolution of 1973. It was meant to circumscribe war-making powers that, the chastened and angry legislature of the day felt, successive presidents had abused. The purpose was to ensure that the solemn decision of commiting the nation's forces along the spectrum of risk, battle and war would be shared by the two branches in an agreed constitutional way.

Except that, from the start, there was no agreement. Mr. Nixon vetoed the bill, and his successors have insisted it infringes unconstitutionally on, among other things, the president's powers as commander in chief; there have been objections on less exalted but weighty pragmatic grounds too. On the 22 occasions since Vietnam when the resolution might somehow have come into play, presidents have picked their way around it, commonly -- as Mr. Bush did on Aug. 9 in respect to Iraq -- reporting to Congress as the resolution demands but insisting they were doing so outside its purview. Presidents have been particularly scrupulous in avoiding the provision that compels a president, 60 days after he moves in armed forces, to withdraw them unless Congress votes otherwise. In the avoiding, they have usually done what Mr. Bush did on Aug. 9 -- pretend blandly that ''involvement in hostilities'' is not ''imminent.'' Like him in this crisis, they have tried to meet the resolution's requirements of consultation, as of reporting, not in the resolution's terms but in their own -- by, for example, inviting members to be briefed at the White House.

There is a case for these circumlocutions and deceits, and it is that the War Powers Resolution, even when presidents skirt its provisions, forces a degree of consultation and openness that otherwise might never be achieved. But this is not a persuasive case. How can the evasive presidential habits that are bred by this resolution and -- this is almost worse -- that have come to be blinked at or only mildly griped at by Congress possibly build respect for either this law or the Constitution itself? The 60-days-and-you're-out provision is especially worrisome: this ''lesson'' of Vietnam imposes a procedure that could too easily invite misunderstanding in a crisis.

Looking at the War Powers Resolution, some conclude that it is right and better and enough that a president be guided by his political instincts than that he be locked in the grip of an inevitably rigid and anachronistic legislative dictate. But to undo the resolution entirely could send presidents a dangerous anything-goes signal and would amount to a historic surrender of powers and responsibilities by Congress. The idea of shared responsibility remains valid and essential.

What is necessary is to flesh out this idea in terms that provide a fair balance of executive flexibility and congressional control and that command reasonable consensus in both branches. The Constitution's separation of powers has aptly been described not as a formula for agreement but as an invitation to struggle. A certain amount of push and pull is even desirable. But it should not be disabling, and in the instance of the awkward 60-day provision, it should not look like Rube Goldberg was one of the Founding Fathers.

One proposal that has been floating around for a while deserves a closer look now -- S. 2, introduced in 1989 by Sens. Byrd, Nunn, Warner and Mitchell. It replaces the automatic requirement for withdrawal of troops after 60 days with expedited procedures for a joint resolution authorizing the action or requiring disengagement. Further, it fills a void in the War Powers Resolution's terms on consultation by creating a standing congressional core group with which the president would regularly consult.

This proposal would not guarantee smooth politics or wise policy, but it acknowledges evident flaws in existing legislation and procedure. Further, it calls into play the genius of American constitutional government -- to bring the judgment of one branch to bear on the judgment of the other in a realm where the most vital national interests are engaged and to ensure that the decisions that result enjoy national support. The Iraq crisis is only the latest passage where the advantages of this approach are apparent.