That panel has pending before it eight separate lawsuits, mostly filed by racial minority groups claiming that the legislature's maps don't come close enough to helping Hispanic and black candidates win proportionate numbers of seats.
Meanwhile, Texas asked the special three-judge federal district court sitting in Washington, D.C. last summer to "preclear" the electoral maps drawn by the legislature under section 5 of the Voting Rights Act.
All states are required by the Court's one-person-one-vote precedents to draw new maps every 10 years, based on census results. The Texas congressional delegation will grow from 32 to 36 seats due mainly to the surge in the state's Hispanic population.
Section 5 requires Texas and all or portions of 15 other states, mostly in the South, to obtain federal "preclearance" -- either by the Justice Department or by the special court in D.C. -- for all changes in voting rules, including electoral maps.
The special court has so far declined to approve the state's maps, setting a January 17 trial date on the "preclearance" issue while saying that the San Antonio court should designate an interim plan for use in 2012 -- as that court has since done.
Four of the more conservative justices criticized aspects of the San Antonio panel's decision as improperly assuming that the state's maps needed to be set aside in their entirety as presumptively violative of minority voting rights.
Justice Antonin Scalia suggested that the state's maps should be used this year in the absence of a more legitimate alternative. But it was far from clear that a majority would support that approach.
The four more liberal justices stressed that the state's maps cannot be used unless and until federally "precleared" as required by Section 5 of the Voting Rights Act.
The likeliest outcome may be a decision sending the case back to the San Antonio panel with instructions to show more deference to the state's maps and to focus on allegations by the plaintiffs that particular districts violate minority voting rights.
This intricate dispute under section 5 has arisen at a time when at least four of the more conservative justices have signaled that they may be prepared to strike down Section 5 itself as an intrusion on state sovereignty that is no longer needed to protect minority voting rights.
But most of the justices appear to be presuming the validity of section 5 for purposes of resolving the Texas case.
The immediate question is whether the 2012 elections should proceed under the maps drawn last spring by the Republican-controlled legislature; under the more Democrat-friendly maps substituted in November by the San Antonio panel, at the behest of Hispanic groups; or under new maps drawn at the direction of the Supreme Court.
Amid the extraordinary pressure to resolve the case on a timetable that would strain any court -- let alone three different courts handling various aspects of it -- Chief Justice John Roberts drew a laugh from the gallery when he asked one of the three lawyers, "When do you expect our decision on appeal from the district court?"
"Later this afternoon," came the response, from Jose Garza, an attorney for Hispanic groups challenging the state's plan, amid more laughter.