ASHINGTON, Oct. 18 - Though too late at least for next month's election, the Supreme Court on Monday gave Texas Democrats a renewed chance to challenge the Congressional redistricting plan that is expected to cost as many as five Democratic incumbents their House seats.

In an unsigned and apparently unanimous order, the justices vacated a ruling issued in January by a special three-judge federal district court in Austin that upheld an unusual mid-decade redistricting imposed by the Texas Legislature's new Republican majority last year over Democratic opposition.

The district court had rejected the Democrats' argument that the new plan, engineered by Tom DeLay of Texas, majority leader of the United States House, was an unconstitutional partisan gerrymander. But the justices ordered the panel to reconsider that decision in light of the Supreme Court's own decision six months ago in a redistricting case from Pennsylvania.

The order was something of a surprise. In the Pennsylvania case, Vieth v. Jubelirer, decided April 28, the court voted 5 to 4 to reject the Democrats' claim of an unconstitutional partisan gerrymander in new Congressional districts drawn by state legislators after the 2000 census. In light of that ruling, some election law experts assumed the justices would deal with the Texas Democrats' appeal simply by summarily affirming the district court's decision. That would have been the end of the Texas case.

Instead, the order to reconsider the decision keeps the case alive and strongly suggests that Justice Anthony M. Kennedy, who cast the swing vote in the Pennsylvania case, agreed with its four dissenters that there is more to say about partisan gerrymandering and the Constitution.

In the Pennsylvania case, Justice Antonin Scalia wrote in an opinion for himself, Chief Justice William H. Rehnquist and Justices Sandra Day O'Connor and Clarence Thomas that claims of political gerrymandering were not the business of the federal courts. The Constitution provides no "judicially enforceable limit on the political considerations that the states and Congress may take into account when districting," he said.

Justice Kennedy, while providing a fifth vote to reject the Pennsylvania Democrats' case, did not join that analysis.

"I would not foreclose all possibility of judicial relief if some limited and precise rationale were found to correct an established violation of the Constitution in some redistricting cases," he wrote in his separate opinion.

The four dissenters - Justices John Paul Stevens, David H. Souter, Ruth Bader Ginsburg and Stephen G. Breyer - all would have permitted the Democrats' lawsuit to proceed under various theories.

As the Texas case returns to the district court in Austin, the question is likely to be whether the circumstances of the 2003 redistricting, particularly that it was the second redistricting of the decade, provide a sufficiently objective indication of undue partisanship to meet Justice Kennedy's test.

After the 2000 census, in which Texas gained two seats in the House, the politically divided State Legislature was unable to agree on a plan and left it up to a federal court to draw one. That plan proved quite favorable to the Democrats, and the Texas Congressional delegation elected under it in 2002 consisted of 15 Republicans and 17 Democrats.

At the same time, however, Republicans gained unified control of the Legislature. They decided to redistrict again, holding successive special sessions as Democrats fled the state to deprive the Legislature of a quorum necessary to conduct business. The new plan shifted more than eight million people into new districts, split one Democratic district into five pieces, and paired six Democratic and Republican incumbents in districts redrawn to favor Republicans.

Five groups of plaintiffs filed lawsuits on a variety of claims, including Voting Rights Act violations as well as partisan gerrymandering. The Supreme Court denied the plaintiffs' request for a stay after the district court upheld the new plan in January. That meant that even though a Supreme Court appeal was pending, the 2004 election would go forward under the new plan.

Paul M. Smith, a lawyer for the Democratic plaintiffs in the lead case, Jackson v. Perry, No. 03-1391, said Monday that even if the challenge ultimately prevailed, there would be no undoing the results of the 2004 election. "It's an unfixable problem now," he said.

In an unrelated case on Monday, the court, accepting an appeal from a Missouri death row inmate, agreed to decide whether his constitutional rights were violated when he was presented to the jury at his sentencing hearing while shackled and handcuffed to a chain around his waist.

The court ruled in the 1970's that it was unfairly prejudicial to a defendant to appear shackled, or even simply to appear in prison clothes, during a trial. The question in the new case, Deck v. Missouri, No. 04-5293, is whether the same principle applies to the separate sentencing hearing that follows a conviction for capital murder. The Missouri Supreme Court rejected the defendant's argument, holding that there was no evidence that the jury had actually been prejudiced. The defendant, Carman L. Deck, confessed in 1996 to shooting an elderly couple to death in their bedroom after robbing them.