When Rep. Charles Pashayan Jr. submitted his honors thesis at Oxford University in 1977, he had no idea what a hot topic it would be six years later. Pashayan (R-Calif.) wrote on "the American legislative veto and its British and constitutional background," a dull-sounding subject if there ever was one.

But last week, when the majority of the Supreme Court said Congress had usurped executive powers by asserting its right to veto specific regulatory and administrative decisions, all hell broke loose.

Although the case involved only a deportation question, the language of Chief Justice Warren Burger's majority opinion was so sweeping that three of the nine justices expressed alarm that it would invalidate "literally hundreds of statutes, dating back to the 1930s."

The majority conceded that the legislative veto was "a useful political invention" for giving Congress a second look at the way in which a rapidly expanding executive branch carried out broad grants of discretionary authority. But Burger said sternly that "policy arguments supporting even useful 'political inventions' are subject to the demands of the Constitution," and the Constitution, in the eyes of six justices, says no-no to this.

So out the window, apparently, went the Reorganization Act provisions, the 1974 budget act, the War Powers Act of 1973 and more than 100 other laws--some nit-picking and some fundamental. One has to say "apparently" about all these things because the sweep of the Supreme Court ruling is implicit, not explicit. That is why Pashayan, among others, was saying last week, "We have to find another case," and ask the court to spell out how far it really meant to go.

But the court could probably use some help. This is one of those rare instances where a blue-ribbon commission--that favorite form of Washington cop-out--may really be useful.

A good starting point for such a commission would be people who have served in both branches of government. Some of them had the most sensible comments I heard on the decision. They made the clearest distinction between the broad areas where the public interest is served by limiting executive discretion, and the narrow cases, like last year's used-car dealer rules, where congressional intervention clearly hampers the executive and serves a special interest.

Rep. Richard Cheney (R-Wyo.), former chief of staff to President Ford, for example, says the court decision "restores a needed balance and ends an era of unprofitable intrusions" into executive affairs by Congress. Cheney says the ruling may force Congress "to focus more on the broad policy decisions and leave their implementation to others . . . to work harder on the original legislation and not count on remedying its defects by taking a second shot." All of which would be good news--if it happened.

On the other hand, another Republican, Melvin Laird, a longtime House member who served as secretary of defense and on the Nixon White House staff, found the decision "extreme" in threatening such measures as the War Powers Act. Laird thinks the issue the court has opened can best be resolved by a "balanced constitutional amendment," which would give the president a line-item veto on appropriations bills, which he now lacks, but make clear the validity of a two- house veto of a wide variety of administrative and regulatory decisions.

Edmund S. Muskie, former Democratic senator from Maine and secretary of state, says the need now is "to distinguish between those procedures that represent a solid evolution in the doctrine of separation of powers and have made historic contributions to government"--which he would say includes the reorganization, budget and war powers acts--and "the almost mischievous efforts of recent years to harass a president and keep strings on an administration."

What all these folks are saying is that there is merit on both sides of this dispute. And good heads like theirs should be put to work suggesting a way to balance the power of the two branches and the policy equities in a constitutional fashion.