THE SUPREME COURT reined in racial manipulation in jury selection yesterday, throwing out the capital conviction of a Texas man named Thomas Joe Miller-El. The court has heard Mr. Miller-El's case before; two years ago, it ordered a lower federal court to take a close look at evidence that prosecutors had systematically excluded African Americans from the jury pool. But the U.S. Court of Appeals for the 5th Circuit all but defied the high court's ruling. The 6 to 3 decision yesterday, therefore, was important both substantively and in emphasizing that lower courts do not get to freelance on questions the Supreme Court has addressed.

Mr. Miller-El's case confronted the court with the question of how blatantly jury selection may be guided by race before it runs afoul of the Constitution. Prosecutors in Dallas, where Mr. Miller-El was prosecuted for a vicious murder, had a history of trying to keep blacks from jury service. A training manual in the 1960s instructed them not to "take Jews, Negroes, Dagos, Mexicans or a member of any minority race on a jury, no matter how rich or how well educated." Such policies were no longer written down when Mr. Miller-El went on trial in 1986, but they lived on. An investigation by the Dallas Morning News revealed that, in 100 cases the newspaper studied, prosecutors removed 92 percent of blacks using peremptory strikes, a procedure in which qualified potential jurors can be removed based on lawyers' whim. The machinations in Mr. Miller-El's case, as the high court has now found, were obvious. Prosecutors, Justice David H. Souter writes, questioned black potential jurors differently from whites and shuffled the roster to push blacks further back in the line of eligibility. Of 11 who were nonetheless deemed qualified, prosecutors then struck 10 using peremptory challenges. While Texas offered the court apparently race-neutral explanations for these strikes, the explanations were not credible. As Justice Souter put it, the selection process was "replete with evidence that prosecutors were selecting and rejecting potential jurors because of race."

Along with another jury bias case the court handed down yesterday, this ruling sends a strong message to prosecutors and lower courts alike that such manipulations are not tolerable.

Justice Stephen G. Breyer, while joining Justice Souter's opinion, wrote separately to make a far broader suggestion: that the court "reconsider . . . the peremptory challenge system as a whole." Justice Breyer noted that despite the court's ban on ethnic jury packing, "the use of race- and gender-based stereotypes in the jury-selection process seems better organized and more systematized than ever before." Indeed, a whole industry and literature has arisen around jury picking. And peremptory strikes are not obviously necessary, since jurors not qualified or fit for service can be removed for cause. In many cases, peremptory challenges serve as a vehicle for lawyer instinct and prejudice. At least as a matter of policy, Justice Breyer's suggestion, which echoes other justices and scholars, deserves careful examination and experimentation.