The Supreme Court upheld Dzhokhar Tsarnaev’s death sentence on Friday, overturning a lower court decision. Dzhokhar Tsarnaev was one of two brothers responsible for the 2013 Boston Marathon bombing, which killed three spectators and a police officer.

The decision was 6-3 in favor of the conservatives and 6-3 in favor of the liberals.

“Dzhokhar Tsarnaev committed heinous crimes,” wrote the majority’s Justice Clarence Thomas. “Nonetheless, the Sixth Amendment guaranteed him a fair trial before an impartial jury. He was given one.”

The Supreme Court’s decision overturned a federal appeals court’s decision to overturn Tsarnaev’s death sentence and ordered a new penalty-phase trial. The lower court stated at the time that Tsarnaev would be imprisoned for the rest of his life for a “unspeakable brutal act,” but that the trial court had made mistakes regarding pretrial publicity and the exclusion of evidence that could have aided Tsarnaev’s case.

Tsarnaev was convicted in 2015 of the deaths of Krystle Campbell, Martin Richard, and Lingzi Lu at the marathon, as well as MIT police officer Sean Collier several days later, among other charges. Tsarnaev and his brother Tamerlan set off two shrapnel bombs near the finish line, littering the sidewalks with BBs, nails, metal scraps, and glass fragments.

Tamerlan would later die in a gunfight with police, but Dzhokhar is being held in a federal prison in Florence, Colorado, following his conviction.

The Trump administration initially requested that the Supreme Court intervene and reinstate the original sentence. The Biden administration renewed the request, referring to Tsarnaev as a “terrorist” who acted in “furtherance of Jihad” and urging the justices to reinstate the jury’s recommendation of death following the “carnage at the finish line.”

Given the Biden administration’s stance on the federal death penalty, it is unclear whether Tsarnaev would be executed. There is currently a moratorium on federal executions while the government investigates the matter. Survivors and family members have disagreed over the years about whether Tsarnaev should be sentenced.

Tsarnaev’s lawyer, Ginger D. Anders, argued that while there is no doubt that the bombings were a “grievous and shocking act of terrorism,” the lower court made two “serious errors” that jeopardized safeguards needed to ensure that her client received an appropriate penalty.

Anders sought to compel information about an unsolved triple murder in Waltham, Massachusetts, in 2011. Investigators began to suspect Tamerlan’s friend, Ibragim Todashev, of being involved in the crime. Todashev initially denied involvement to agents, but later requested a deal. He claimed he was involved, but Tamerlan was the one who murdered the victims by slitting their throats. Todashev had started writing a confession but was attacked by agents, who shot and killed him.

Anders sought to include the evidence because she argued it supported her client’s claim that he did not deserve the death penalty because he was only acting under the direction of his older brother, who played a much larger role in carrying out the marathon bombings, as evidenced by his previous experience.

In dissent, Justice Stephen Breyer, writing for his liberal colleagues Justice Elena Kagan and Sonia Sotomayor, stated that the evidence should have been heard by the jury.

“This evidence may have led some jurors to conclude that Tamerlan’s influence was so pervasive that Dzhokhar did not deserve to die for any of the actions he took in connection with the bombings, even those taken outside of Tamerlan’s presence,” Breyer said.

Breyer said, “where death is at stake the courts (and Congress) believe that particular judicial care is required.”