The Supreme Court building in Washington. (J. Scott Applewhite/Associated Press)

Gerald Kogan, a former assistant state attorney and chief prosecutor in the Dade County, Fla., State Attorney’s Office, served as a justice on the Florida Supreme Court from 1987 to 1998, including two years as chief justice. Tim Cole served as an elected Texas district attorney from 1993 to 2006. The authors are co-signers of an amicus brief filed in the Buck case.

As former prosecutors, we recognize that the state’s decision to seek a death sentence involves the utmost ethical responsibility. Capital cases, more than any other, require meticulous adherence to prosecutorial ethics. Thus, the prosecutors’ ethical code, adopted by the National District Attorneys Association, as well as the U.S. Constitution, make clear that no death sentence can be based on a factor as arbitrary as race.

But the pernicious use of race, among other troubling issues, including astonishingly ineffective defense lawyering, is at the center of the Duane Buck death-penalty case, which will be argued to the Supreme Court on Wednesday.

Following Buck’s 1997 conviction in the murder of his former girlfriend and her friend, Buck’s court-appointed trial counsel relied on an “expert” who testified during the trial’s sentencing phase that, because he is black, Buck was more likely to commit violent crimes in the future. Setting aside for the moment that this claim is patently false, it was particularly significant because in Texas, jurors must find that a defendant will pose a “future danger” before they can impose a death sentence. The prosecutor, on cross-examination, asked the expert to repeat his opinion that Buck’s race increased the probability that he would be a danger in the future and, at closing, encouraged the jury to rely on the expert’s testimony in support of a finding of future dangerousness. After deliberating for two days, and requesting the expert reports, jurors found Buck to be a future danger and he was sentenced to death.

This is an extraordinary case that demands extraordinary relief. One reason is the uniquely injurious nature of racial discrimination itself. The testimony connecting Buck’s race to his likelihood of dangerousness not only deprived him of his fundamental right to a fair trial, it also compromised the integrity of the criminal-justice system overall. An assessment of future dangerousness is properly based on an individual’s personal history, not on innate, immutable traits.

It is also extraordinary because Texas recognized the unconstitutional nature of the testimony and promised Buck a new sentencing hearing, but incomprehensibly refused to honor that promise.

In 2000, Texas’s then-attorney general, John Cornyn, became aware of this particular expert’s problematic testimony about race and future dangerousness when another capital defendant challenged it in a U.S. Supreme Court appeal. On behalf of the state of Texas, Cornyn admitted that the introduction of such testimony “violated [the defendant’s] constitutional right to be sentenced without regard to the color of his skin.” He agreed to have the defendant’s sentence vacated so that a new sentencing hearing untainted by such racial discrimination could be held.

Following that concession, Cornyn conducted a thorough investigation of Texas’s death row to determine if any other cases were similarly tainted by this expert’s unconstitutional race-equals-dangerousness testimony. His office concluded that the sentences of six death-row inmates, including Buck, were poisoned by such evidence. Texas promised new sentencing hearings for all six prisoners but, without explanation, reversed course in only Buck’s case.

The failure of the prosecutors involved in this case to honor their ethical and professional obligations has been compounded by the failure of the judiciary to recognize the urgent need for relief. Incredibly, the U.S. Court of Appeals for the Fifth Circuit denied Buck’s request for permission to appeal the denial of relief on his resentencing request, declaring that Buck had “not made . . . even a minimal showing that his case is exceptional” as required under the relevant federal rule.

We would be hard-pressed to think of a more extraordinary case. Prosecutors play a critical role in maintaining public confidence in the criminal-justice system. They are entrusted with the responsibility to seek justice and enforce state and federal law. In Buck’s case, that trust was violated by the trial prosecutor’s exploitation of the defense counsel’s constitutionally deficient performance in introducing the race-as-dangerousness testimony and by the Texas attorney general’s failure to keep his promise to ensure that Buck received a new, fair sentencing hearing.

Our Constitution, and the integrity of our criminal-justice system, require more from our prosecutors. We call on the Supreme Court to grant relief to Duane Buck so that he may obtain the new, colorblind sentencing trial that Texas promised him.