WASHINGTON -- The computer is never mentioned in the Constitution, but the Supreme Court is finding it to be the source of some formidable constitutional puzzles as the justices get ready to rule again on congressional redistricting.
These days, the justices are looking over a handful of new cases testing district lines drawn specifically to give black candidates a better chance of winning election to the House -- particularly from districts in the South.
The Supreme Court has said that those districts may be an unconstitutional form of "racial gerrymandering," if they are drawn up in such a "bizarre" form that they actually stand for nothing except racial segregation of voters.
Such districts bear "an uncomfortable resemblance to political apartheid," as Justice Sandra Day O'Connor put it when the court last ruled on the subject in 1993.
The court, however, has not said exactly what makes a district "bizarre" enough to turn it into a constitutional violation.
It has suggested that, at least in some cases, a bizarre shape might be explained away. But the court has not spelled out what kind of explanation would do.
Clarifications may come, perhaps before summer, in some of the cases now on the docket.
The court already has taken on a case from Louisiana for decision, may soon act on one from Texas, and has cases from Georgia and North Carolina (and even one from California) awaiting action.
A case from Worcester County, Md., testing the use of race in redistricting the Board of County Commissioners, also could be affected by the outcome of the new congressional cases.
Maryland's congressional districts already have been upheld by the court.
As the justices look more deeply into the cases, however, they are discovering that the magic of the computer has become both the deft solution to political complexities in redistricting and part of the hard problem of invalid "racial gerrymandering."
The computer is the tool legislators put to work when they try to sculpt a new district that satisfies all kinds of political and legal needs, while making sure simultaneously that some districts will have a clear-cut black majority that can control election outcomes.
That means, apparently, something close to a black voting-age population of 55 percent or 60 percent.
Black-dominated districts are one of the remedies that federal voting rights law and the Justice Department demand to make up for political isolation of blacks in congressional elections.
Legislatures in the South, in creating new districts after each new census, often meet a Justice Department veto of their plans if they don't create black districts.
The computer, each case before the court illustrates, has made it possible to put widely scattered pockets of black voters into a new district and at the same time save the seats of incumbents, create districts that are almost exactly equal in population, and pay off competing political demands.
In one of the cases, a computer whiz demonstrated this magic while lower court judges watched on monitors.
Among the things the judges saw: It was possible to create two new black-majority districts for that state (North Carolina) while creating a total of 12 new House districts with seven of them taking in 552,386 people each, and five including 552,387 each.
The Supreme Court demands that kind of equality, under its one-person, one-vote decisions.
It is when the computer finishes its job that the Supreme Court has found that constitutional problems begin to set in, and those are the puzzles the justices must now try to solve.
With districting plans keyed in exhausting detail to census data about people, their race, and where the live, the computer may produce a visual maze -- and a verbal one, too.
Not only can a computer pinpoint blacks where they now live, it also can reach out and put them into a district even if they have moved to another part of town, by tracing their move from one census bloc to another -- as a computer did for the legislature in Texas.
The judges in the Texas case remarked in striking down three districts:
"If these districts -- tortuously constructed block-by-block and from one side of the street to another . . . to satisfy the desired racial goal -- are constitutional, then the state could more easily hand each voter a racial identification card and allow him to participate in racially separate elections."
Some of the Texas districts are so complicated, the judges remarked, that it takes a wall map 3 feet square to show where the boundary lines actually go in a community.
And those large maps illustrate how nimble the computer was in jumping over a street, through a neighborhood, around corners, and across town to link voters in a district by their race.
Verbally, lower court judges have found themselves pressed to find colorful and apt imagery to describe the results of the computer run -- including such phrases as "a bug splatter on a windshield," "the sign of Zorro" or "a DNA molecule."
The days of the historically familiar and easily described "salamander" district -- the kind that gave rise to the word "gerrymander" -- seem to be gone.
But the verbal challenge goes beyond merely finding a descriptive metaphor.
North Carolina, for example, used to have a law describing its congressional districts, before the computer was put to work on them.
The language of the former law occupied page and a half. But, when new districts were generated by computer, the new law ran to 66 pages of 37 lines each.
A sampling of just three lines from one district's description in the new law: " . . . Block 253B, Block 254, Block 255, Block 256, Block 257, Tract 0009, Block Group 1, Block 108, Block 109, Wilson J *, Wilson K *, Wilson L *, Wilson M *, Wilson P *."
In an attempt to provide some explanation, a clause later in that law says: "Boundaries are as shown on the IVTD Version of the United States Bureau of the Census 1990 TIGER Files, with such modifications as made by the Legislative Services Office. . . . "
North Carolina's plan has a special distinction of its own: Two of the districts actually leap over each other.
The representative seeking to tour his or her district must pass through a slice of a colleague's territory to do it.
And, opponents of the North Carolina plan have told the court, two of the state's House members do not live in the districts they have been chosen to represent.
They need not live in the district in which they run, under North Carolina law, although politicians generally prefer to live among their constituents.
In other parts of that state, and in other states, however, the computer was able to meander through one incumbent's district and pull out an incumbent's home precinct so that he or she could still run there.
The computer's ingenuity, some courts have acknowledged, does almost everything in some states except draw small and compact legislative districts.
It is now up to the Supreme Court to say whether that is a failing that violates the Constitution.