SOME POLITICAL thicket: that's what Supreme Court justices may think as they read the papers filed in the Indiana redistricting case. The Republican National Committee has filed a brief supporting the position taken by Indiana's Democratic Party. California Democrats have filed a brief supporting the Indiana Republicans. The justices may be wondering how to get out of this particular thicket in a way that preserves the principles of the one-man, one-vote rule and general fairness, but doesn't burden the courts with dozens of redistricting cases in the future.

This case arises because, in that most partisan of states, Indiana, Republicans redrew the state's congressional and legislative district lines so as to maximize the number of Republican districts. No surprise. No surprise either that the Indiana Democrats sued in federal court, hoping to find a sympathetic court. They got a court with two judges appointed by Democrats, and the court ruled 2 to 1 that the Republican plan violated the Constitution. The Indiana Democrats' glee was shared by national Republicans, since their party controls few legislatures outside Indiana; the Indiana Republicans' chagrin was shared by Democrats in California and elsewhere, who would like to draw district lines without having them overturned by courts.

Fortunately, there is a way for the court to preserve one-man, one-vote and minimize judicial intervention. It is to rule for the Indiana Republicans and the California Democrats. Some will say this sanctions gerrymanders. That's true, in the sense that it will ratify the inevitably partisan decisions of legislators in this most partisan area of lawmaking. But the partisan advantage any majority can get in redistricting is already greatly limited by strict application of the one-man, one-vote rule. Even an ingenious redistricter is unlikely to produce a plan that, over the 10-year period the typical plan is in effect, will bar the opposition from winning control. Indiana is instructive here. Despite all the Republicans' efforts, Democrats hold five of the state's 10 congressional districts, including two that were clearly intended for Republicans.

Any rule that allows courts to overturn districting plans for any reason except population disparity or racial unfairness will ensure a continuing flow of litigation. If the court says that a plan may be overturned because of egregiously misshapen districts or failure to adhere to state and county lines, you can be sure that every party that loses a redistricting fight will be on the lookout for a judicial forum where it can win. The Supreme Court's duty, on the other hand, is (a) to see that principles of basic fairness apply, by seeing that every plan's districts vary in population by no more than the census's margin of error, and (b) to keep the courts otherwise out of a business that is purely political, by saying that such a plan, whatever its partisan motives, will be upheld. It could do both by leaving the Indiana redistricting alone.