That’s why North Carolina lawmakers in 2009 passed the Racial Justice Act, after a string of exonerations of black men on death row who had faced all-white or nearly all-white juries. One of the first laws of its kind, it allowed a death-row inmate to have his or her sentence reduced to life by presenting statistical evidence of a pattern of racial discrimination by prosecutors.

In North Carolina, showing that pattern was easy. A study by researchers at the Michigan State University College of Law looked at jury selection in 173 North Carolina death-penalty trials over 20 years and found that black jurors were struck at twice the rate of whites . In a state that is more than one-third nonwhite, roughly half of the state’s current death-row population was convicted by all-white juries or juries with only one black juror.

More than 130 condemned men and women brought claims under the Racial Justice Act. In 2012 the first plaintiff, a death-row inmate named Marcus Robinson, won his case. Three more cases followed, all with the same result: The court found not only a pattern of racial discrimination by prosecutors, but also that they had purposefully discriminated in each of the cases. All four inmates were resentenced to life without parole. (Two other inmates whose cases are being reviewed were in the process of seeking relief when the Racial Justice Act was repealed.)

But even as the new law was exposing the scope of racial discrimination by North Carolina prosecutors, the state’s Republican legislature was trying to wipe it off the books. In 2011, lawmakers passed a bill gutting the Racial Justice Act, but it was vetoed by the Democratic governor, Beverly Perdue. When Ms. Perdue was replaced in 2013 by Pat McCrory, a Republican, the now-unified government wasted no time in dumping the law.

With the racial-justice act out of the picture, the state appealed the re-sentencings in the four cases that had been decided under it, and in 2015, the North Carolina Supreme Court sent the cases back for further review, because the state had not been given enough time to respond to the Michigan State study on biased juror strikes.

Shortly after, state officials disregarded the state Supreme Court’s order and returned the four plaintiffs to death row without a court holding hearings or considering new evidence or arguments. The state still has not provided any explanation for the racial discrepancy in juror strikes, arguing only that the repeal of the law means the plaintiffs go back to death row.

In the state Supreme Court next week , these plaintiffs, including Mr. Robinson, will make numerous constitutional arguments, but they all boil down to the same issue: State lawmakers passed a law to find racial bias in their justice system. They found it. Rather than build on that success, new lawmakers repealed the law and re-punished the people who had benefited from it. These plaintiffs aren’t bringing claims of innocence; they are arguing that they deserve the same constitutional protections as anyone else, including against double jeopardy.