LAST SPRING, when the gasoline lines were at their longest, Congress was unable to get a mojority together for any rationing plan. Every part of the country passionately believed it was being victimized, or was about to be victimized, by every other part. Now autumn has come, and people's sense of grievance has diminished. At last, Congress has produced a rationing law -- of sorts.

The striking thing about this law is the inordinately intricate character of the safeguards that it applies to both writing and imposing the plan. It's the legislative equivalent of a lock that opens only with three keys held by different people who do not entirely trust each other. The bill tells the president to draw up a plan, but provides that Congress can veto it by a vote of both houses. The president could veto the veto, but Congress could in turn override that veto with a two-thirds vote. Once approved, the plan could be ordererd into effect by the president. But Congress could again overrule him, this time with a vote of either house.

Congress is apprehensive that a president might be tempted to invoke rationing too easily, to meet the public outcry in another limited and temporary shortage like last spring's. Most voters take it for granted that rationing would be a fair and efficient solution. But most congressmen have been through a highly educational process of hearings and debates, and they know better. Rationing would be rough justice at its roughest. That's who Congress has also said rationing could be imposed only in a truly dire emergency -- the kind of shortage that might be caused by a war in the Persian Gulf, for example, or a coup in Saudi Arabia. Congress doesn't like the idea of rationing, and it passed the bill only because it knows that a desperate emergency could occur without warning.

To avoid gasoline lines in less severe shortages and to hold down oil imports, the most sensible policy is to decontrol gasoline prices immediately. The House, which voted for decontrol two weeks ago, has now reversed itself -- which is a pity. But the earlier vote demonstrated that a good many people at the Capitol have come to see that the controls are doing the country more harm than good. That, at least, is progress.