WASHINGTON — The Supreme Court seemed to side with Duane Buck, a condemned man, during oral arguments Wednesday involving a decades-old Texas death-penalty case that included racially discriminatory references during court testimony.

In 1997, Buck was sentenced to death for the murders of his former girlfriend and her friend. His guilt for the 1995 killings is not in question; rather, the court is tasked with considering whether racially charged testimony during his sentencing hearing warrants a certificate of appealability, which could result in a new hearing.

For a death sentence in Texas, state law requires the jury to decide the defendant will likely be a continued violent threat to society.

During the 1997 hearing, the prosecutor asked defense witness Walter Quijano, then a psychologist, “You have determined … that the race factor, black, increases the future dangerousness for various complicated reasons. Is that correct?”

“Yes,” Quijano said, according to court documents.

“What competent counsel would put that kind of evidence before a jury?” Justice Ruth Bader Ginsburg asked Wednesday.

Buck’s lawyer, Christina Swarns, told the eight-member court that the Louisiana-based 5th U.S. Circuit Court of Appeals held Buck to an unduly burdensome standard in its August 2015 denial of his ability to appeal his sentence.

Swarns called the lower court’s integrity into question because it ruled against Buck in spite of Quijano’s testimony. She said the court’s analysis “completely ignored the heart of the case.”

Three factors, she said, play in Buck’s favor: the racially biased testimony, the severity of the death penalty, and the consistent and unrelenting diligence Buck has shown in his appeals to the courts.

Texas Solicitor General Scott Keller, who defended the state, said Quijano’s testimony was only one of the factors that played into Buck’s “future dangerousness,” citing domestic violence allegations from an ex-girlfriend and his lack of remorse after the murders.

The fact that the defense introduced Quijano as its witness should also make a difference, Keller added. When the state uses race as an aggravator, he said, it’s more prejudicial than if used by the defense.

Justice Elena Kagan disagreed with this assessment, saying it would be more prejudicial for the defense to do so, because the jury believes the defense works in the best interest of the defendant.

“Why does it matter who uses race?” said Justice Sonia Sotomayor. “We say neither (prosecution nor defense) should use race in a negative way against a defendant.”

Both Kagan and Sotomayor dissented from the court’s 2011 decision to deny Supreme Court review of Buck’s case. But a 2013 Supreme Court decision in another case provided an opportunity for Buck to appeal again in federal court.

Another issue argued was a potential overreach by the 5th Circuit Court in obtaining a merits review on the claim that Buck had ineffective counsel. Kagan said the court went outside of its jurisdiction, which is only to determine if the claim is debatable.

“The 5th Circuit has not scrupulously adhered to the application of the COA (certificate of appealability) standard,” Swarns said, describing the court’s actions as “out of line.”

The high court ruling will likely come at the end of June.