The Supreme Court ruled yesterday that an African American on death row in Texas should get another chance to have his sentence overturned because of alleged racial bias at his 1986 murder trial -- a decision that sent a firm reminder to state and lower federal courts that they must guard against constitutional violations in the criminal justice system.

By a vote of 8 to 1, with Justice Clarence Thomas dissenting, the court ruled that the New Orleans-based U.S. Court of Appeals for the 5th Circuit should have granted Thomas Joe Miller-El a hearing on his claim that Dallas County district attorneys violated his constitutional right to a discrimination-free trial by summarily excluding 10 out of 11 blacks who were eligible to serve on the jury in his case.

"In this case, the statistical evidence alone raises some debate as to whether the prosecution acted with a race-based reason when striking prospective jurors," Justice Anthony M. Kennedy wrote in the opinion of the court.

Capital punishment foes and advocates of changes in the criminal justice system had argued that Miller-El's case was an egregious example of why many Americans, especially minorities, distrust state criminal justice systems. And a Supreme Court that has not often looked favorably on defendants' efforts to reverse state criminal judgments seemed to agree.

"The court is saying that the job here is not to rubber-stamp the state courts, that you have to be vigilant about having the opportunity to check constitutional violations," said Diann Rust-Tierney, director of the American Civil Liberties Union's Capital Punishment Project.

In his dissent, Thomas said Miller-El's "arguments rest on circumstantial evidence and speculation."

The Miller-El case was one of many cases brought in recent years by death row inmates trying to sustain constitutional claims in the streamlined federal death-penalty appeal process set up by Congress in the 1996 Anti-Terrorism and Effective Death Penalty Act (AEDPA). The law limited death row inmates' ability to challenge their sentences in federal court, thus making them more dependent on state courts for the protection of their constitutional rights.

AEDPA embodied an approach favored by Chief Justice William H. Rehnquist and other conservative members of the Supreme Court, but yesterday's eight-member majority showed that there are still limits to the deference the federal judiciary gives to state court rulings.

Yesterday's ruling could help some state inmates get federal court reviews of their sentences, particularly in the 5th Circuit, whose jurisdiction encompasses Texas, the country's leading death penalty state. That, in turn, means that state courts will have to take more care in reviewing claims of racial bias and other constitutional violations, legal analysts said.

In turning down Miller-El's request for a hearing, the 5th Circuit appeals court had said that he lacked "clear and convincing" proof of racial bias, but this was the wrong legal standard, the Supreme Court ruled. The high court said that, to gain a hearing, all Miller-El needed to show was that his claim "was debatable among jurists of reason."

To prove racial discrimination in the use of peremptory strikes by the prosecution, Miller-El must show that prosecutors had no credible race-neutral reason to exclude a disproportionate number of blacks. And, under AEDPA, he will still have to produce "clear and convincing" evidence that the state judge who ruled that his evidence "did not even raise an inference of racial motivation" was wrong.

Though that question was not for the high court to decide, the justices seemed to credit Miller-El's case. Kennedy wrote that it was "relevant" that the Dallas County district attorney's office had been "suffused with bias" in the past, including in the use of a 1963 circular instructing prosecutors, "Do not take Jews, Negroes, Dagos, Mexicans . . . on a jury." Kennedy accused both the state court and the 5th Circuit court of a "dismissive and strained interpretation" of the facts.

A jury of nine whites, an Asian American, a Latino and an African American found Miller-El guilty of capital murder in the brutal slaying of a Holiday Inn employee, Doug Walker, in November 1985.

Miller-El alleges that the prosecutors manipulated the jury pool by asking potential black jurors deceptive and leading questions, and by exploiting a unique Texas practice called a "jury shuffle" to move blacks out of the front rows of the jury pool.

All of this, Miller-El argues, reflected the lingering influence in 1986 of longstanding discriminatory practices in jury selection by the Dallas County district attorney -- as evidenced by testimony from former prosecutors and internal documents. Prosecutors counter that their office had ended its racially biased practices by 1986 and that what Miller-El depicts as racial discrimination was actually a race-neutral effort to find and remove potential jurors who would be reluctant to impose the death penalty.

Justice Antonin Scalia wrote separately to say that, although he agreed with the majority's legal interpretation, he thought the Texas authorities had a plausible case.

In his dissenting opinion, Thomas flatly agreed with them. He noted that prosecutors aggressively questioned both white and black jurors who seemed ambivalent about the death penalty.

He said that the 5th Circuit court was right in this case to insist on "clear and convincing" evidence of state court error before permitting Miller-El a hearing, adding that "the simple truth is that petitioner has not presented anything remotely resembling 'clear and convincing' evidence of purposeful discrimination." Thomas called the evidence of past discrimination by the Dallas district attorney "entirely circumstantial."

The case is Miller-El v. Cockrell, No. 01-7662.

Justice Anthony M. Kennedy faults lower courts' "dismissive and strained interpretation" of facts.