Twice in the past three weeks, the Supreme Judicial Court has overturned first-degree murder convictions for cases in Dorchester over what it said were errors by the trial judges in not pressing prosecutors to prove they were not trying to bar prospective jurors because of their race.

On Aug. 31, the state's highest court ordered a new trial for Anthony Robertson, convicted of fatally shooting Aaron Wornum in the head on Sumner Street in June, 2011. At issue for the SJC were the Suffolk County District Attorney's "peremptory" rejections of two men from consideration as jurors - both sides are allowed to strike prospective jurors without giving a reason, at least as long as there is no racial bias

This week, the court vacated George Ortega's conviction for the 2012 murder of Steven Fuentes on Leyland Street, saying the judge in the case should have should have pressed prosecutors more on their decision to try to exclude a black woman from the jury - and should have told the jury to consider whether Fuentes's death was a case of self defense.

In both cases, the Suffolk County District Attorney's office will ask the court to reconsider its rulings, saying the justices overlooked evidence that showed no bias.

In the Robertson case, at issue for the SJC were the Suffolk County District Attorney's "peremptory" rejections of two men from consideration as jurors - both sides are allowed to strike prospective jurors without giving a reason. One of the men was black, the other, born in the Dominican Republic, was the subject of an argument between the prosecution and the defense as to whether he was black or Hispanic.

In either case, Robertson's attorney argued their rejection showed a racial bias by the prosecution and asked Suffolk Superior Court Judge Patrick Brady - who died in 2016 - to probe the issue.

Brady refused, saying the fact the empaneled jurists already included several people of color showed there was no bias. He did ask the prosecutor to respond to the bias allegation about the second man - the one from the Dominican Republic. The SJC reports the DA responded to the question like this:

"To be perfectly blunt and I'm going to keep my voice down, he didn't seem like the most intelligent guy. He's like a nice enough guy but he didn't seem all that intelligent.

"And, most importantly, I don't consider him African-American. Whether he has African blood in him or not, I have no idea. He was born in the Dominican, I consider him Hispanic."

Brady, who noted that man had a lighter skin color than Robertson, then told the defense attorney he would go no further because the presence of two black women on the jury showed a lack of bias.

Wrong, the SJC said - Brady should have questioned the assistant DA more, to rule out any possible racial bias.

"We conclude therefore that the judge abused his discretion in finding no pattern after the defendant's second objection to the Commonwealth's use of peremptory challenges on black men. Because such an error is structural, carrying the presumption of prejudice, we vacate the convictions and remand the case for a new trial."

In the Ortega case, the SJC said Suffolk Superior Court Judge Linda Giles should not have let prosecutors reject a prospective juror who was a black woman without explanation after she had already warned them about possible bias when they had earlier rejected a black man.

With that first prospective juror, the judge asked prosecutors to prove they were not seeking to reject him simply because of his race; she agreed to let him be excluded because of his "failure to accurately disclose his criminal history on his jury questionnaire," the court said. But with the woman, the judge rejected a request from Ortega's attorney that the prosecution make a similar effort to prove non-racial bias because they had already allowed another black woman on the jury. Giles should have pushed prosecutors to provide the same proof as with the man to ensure they were not rejecting her because of her race.

A spokesman for Suffolk County District Attorney Dan Conley said his office will ask the court to take a second look:

"The SJC inexplicably chose to omit from its decision the fact that [the woman]'s brother had been arrested by Boston Police, prosecuted by the Suffolk DA's office, convicted by a Suffolk County jury, and imprisoned by a Suffolk County judge. The trial prosecutor exercised his challenge only after she had disclosed this information and stated her belief that it was unfair. These facts, all on the record before the high court and part of the prosecution brief, clearly explain the prosecutor's actions and support the judge's finding that those actions were proper.

"The facts supporting the prosecutor's reasoning in this case are especially important because District Attorney Conley mandates that his staff approach their cases honestly and ethically, without bias or prejudice. Suffolk prosecutors recognize that the fairness of a trial at every stage, including jury selection and composition, is every bit as important as the verdict. They recognize and embrace their duty to protect the integrity of the process and they receive constant training to ​help them do so. The high court and the public should know that our first duty is to the interests of justice, and that we strive to pursue them with the highest levels of fairness and integrity.

"In the federal courts, post-conviction peremptory challenge claims like this can be resolved through evidentiary hearings where lawyers and judges can testify to their decision-making processes. If those processes are fair and proper, as the trial prosecutor's was in this case, there's no need to vacate the jury's verdict - or unfairly impugn the integrity of a respected and ethical lawyer. Massachusetts courts should consider the same method rather than proceeding directly to the 'nuclear option' of reversal on incomplete evidence."

But even aside from the jury-selection issue, the court said it had to overturn the verdict because Giles made another critical mistake at the end of the trial, by rejecting a request from Ortega's lawyer that the jury be instructed to consider whether Ortega shot Fuentes in self defense as the two pot dealers argued over whether Fuentes was infringing on Ortega's turf.

The SJC said testimony had raised valid questions about the prosecution case and the jury should have been told they could consider Ortega's self-defense argument: "Specifically, there was testimony from which the jury could infer that the victim not only escalated the confrontation by displaying a gun, but also tried to shoot the defendant before the victim himself was shot. This evidence, considered in combination with testimony concerning the confrontation between the victim and the defendant earlier that day, would be sufficient to permit a rational jury to find a reasonable doubt whether the defendant had a reasonable and actual belief that he was in imminent danger of being killed or seriously injured."

The DA's office argues against this, as well:

"First, Ortega was the aggressor who showed up on the victim’s street with an armed group, seeking to avenge a prior slight. Second, the courts have historically required evidence that the defendant actually feared for his life or safety at the time he used deadly force, not just that he could have been afraid. No such evidence emerged in Ortega’s case."