The Supreme Court agreed last month to hear yet another redistricting case. An Indiana federal court (2-to-1 Democratic) ruled that plans drawn by Republicans deprived Democrats of their right to equal protection under the Constitution. Some members of the high court, to judge from last year's ruling in a New Jersey case, are determined to get the politics out of redistricting.

Let me give the court some advice from a one-time partisan redistricter. You've got about as much chance of getting politics out of redistricting as King Canute had of getting the North Sea off the east coast of England. All you're going to do, if you extend the New Jersey ruling, is extend the politics of redistricting from the legislatures, where it belongs, to the courts.

If you affirm the Indiana court, every aggrieved party -- and there's always at least one -- will be politically derelict if it doesn't take every redistricting plan to court to see if it can't wangle something better out of some friendly or naive judges. The alternative -- the better choice legally and politically -- is to leave well enough alone. Just let stand any redistricting plan in which the population of the district differs by less than the statistical margin of error from the census on which it is based.

Yes, doing that leaves politics in redistricting. Republican legislators in Indiana will help Republicans win elections, and Democratic majorities in California will help Democrats. But what you justices may not realize, because so far as I know none of you ever tried to draw a partisan redistricting plan yourself, is that the equal-population standard in effect for 21 years now imposes limits and discipline on partisan redistricters sufficient to prevent irreparable mischief. It is exceedingly hard -- in fact, two decades of history in 50 states shows that it is nearly impossible -- for even the most partisan redistricter to put a legislature or a congressional delegation out of the reach of the other party over the 10-year period between the censuses that trigger redistricting. Some time during that period, the other party's fortunes rise enough that it captures all those 52-percent districts that you so carefully carved out for your party, and control of the legislature changes hands. I redistricted the Oakland County, Mich., Board of Supervisors for the Democrats 16 years ago. It's had a Republican majority since 1972.

Before the one-person-one-vote ruling, it was possible to put a legislature totally out of reach. When I first started following elections, Michigan had state senate districts drawn on the basis of the 1910 census; in 1958, Democrats won 58 percent of the votes for state senate and won 12 of the 34 seats. That happened when courts allowed states to violate the population standard in order to honor city and county lines -- a standard some critics would like to return to. But such irreparable political harm simply can't happen under the equal-population standard, no matter how grotesquely shaped or partisanly motivated the district lines. The one-person-one-vote rule allows gerrymandering but places strict limits on its effectiveness.

But shouldn't we ban gerrymandering altogether? Maybe we should -- maybe we could -- if there were such a thing as a purely neutral redistricting plan. But, of course, there isn't. Take an area the western half of which is 75 percent Republican and the eastern half 45 percent Republican. Assume it's entitled to two districts. Splitting it up and down gives you one Republican and one Democratic district. Splitting it across the middle gives you two Republican districts. Which is fairer? Fiorello LaGuardia said there was no Republican or Democratic way to sweep the streets. Well, there's no nonpartisan way to redistrict legislative seats.

And don't believe anyone who tells you that some nonpartisan expert or computer is going to draw a neutral plan. Anyone or anything smart enough to draw district lines is smart enough to know or to find out that San Francisco is Democratic and Orange County Republican -- and to figure out how many Republicans and how many Democrats would have been elected in his, her or its districts last time out.

So leave the politics to the politicians. Just stick closely to the 21-year-old equal-population standard. Naturally, the politicians who have been on the losing end of redistricting plans (Democrats in Indiana, Republicans most other places) will cry out that they're being threatened with extinction. But remember that these are the appeals sent out in fund-raising letters, which always aim to convince the recipient that if he doesn't send in his $15 right this minute, Western Civilization will end. It won't. And redistricting won't make anybody's party extinct if you just announce that you -- and all those lower courts whose often wacky and unpredictable decisions you're understandably tired of reviewing -- will automatically approve any redistricting plan that complies with the equal-population standard.