THERE IS something slightly obsessive about the Supreme Court's decision in the New Jersey voting rights case. By 5 votes to 4, the court rejected the state's recent congressional redistricting plan on grounds that the districts' populations are unequal. The smallest district has 0.43 percent fewer people than the average--2,261 fewer people, in a district of more than half a million. The court said that a Rutgers professor had offered a plan with a still narrower variation, and the state had produced no good reason for not accepting it. But won't there always be somebody with a plan that is, by some hundredths of a percentage point, better?

This decision revolves around a districting plan that is, by any broader standard, an atrocity. It is flagrantly gerrymandered; one congressional district runs by a highly indirect route from the Philadelphia suburbs on the western edge of the state to the New York suburbs in the northeast. The plan was drawn up by Democrats for the most explicitly partisan purposes, and the minor variations in the districts' populations is the least of its defects.

On the same day that it handed down the New Jersey case, the court told the state of Wyoming that its legislative districting plan is permissible--although there the smallest legislative district has 60 percent fewer people than the average. The issue was Wyoming's rule that every county, including the most sparsely settled, gets at least one representative in the legislature. The court--speaking, as you might imagine, through quite a different majority--held that the preservation of county boundaries in state elections is a "longstanding and legitimate policy" that justifies the disparity in population.

The court has traditionally accepted somewhat larger variations in state election districts than in federal. But the difference between the unconstitutional 0.43 percent in New Jersey and the constitutional 60 percent in Wyoming struck even the judges as--well--awkward.

Justice White, dissenting in both cases, suggested that a majority seems to be forming for a broader rule than the tyranny of arithmetic. Justice Stevens provided the crucial fifth vote in the New Jersey case, in a concurring opinion that showed where that majority might be going. Absolute arithmetical equality among districts is not only impossible, he said, but insufficient to guarantee equal representation--certainly the right conclusion to be drawn from contemplation of the New Jersey districts. He observed that compactness of districts, and regard for established political boundaries, deserve attention in these cases. Another criterion is whether any group of voters--a racial minority, for example--has been put at a disadvantage, and whether the state can produce any acceptable explanation.

The court clearly finds its present posture uncomfortable, and these cases indicate that it may shortly try to find its way to higher ground. You need not fear that any injustice has been done to the state of New Jersey. Quite the contrary. But that decision invites an avalanche of litigation on the most trivial inequalities in districting plans all over the country. The court needs a standard of fairness that is less fanatically arithmetical, and broader in its vision.