Supreme Court conservatives appear ready to endorse death sentence for Boston Marathon bomber Dzhokhar Tsarnaev

The justices appeared to be divided along familiar ideological lines, however, as they considered a federal appeals court decision that wiped away the sentence citing errors made by the district court concerning the admissibility of a piece of evidence.

Conservatives on the bench suggested that the evidence was unreliable and should not have been presented to the jury.

But the three liberal justices said it pertained to the heart of Tsarnaev's argument: that he should not receive the death penalty, because it was his brother who took the lead in executing the bombing.

Tsarnaev was convicted in 2015 in the deaths of Krystle Campbell, Martin Richard and Lingzi Lu at the marathon and Massachusetts Institute of Technology police Officer Sean Collier several days later, among other charges. Hundreds were injured after Tsarnaev and his brother Tamerlan set off two shrapnel bombs near the finish line, leaving the sidewalks strewn with BBs, nails, metal scraps and glass fragments.

Tamerlan Tsarnaev would later die in a gunfight with police. Dzhokhar Tsarnaev is being held in federal prison in Florence, Colorado.

In July 2020, a federal appeals court said that Dzhokhar Tsarnaev will remain in prison for the rest of his life for "unspeakably brutal acts" but that he should be given a new penalty-phase trial, citing issues concerning juror selection and pretrial publicity as well as the exclusion of evidence that may have helped his case.

The 1st US Circuit Court of Appeals vacated the death penalty with directions to hold a new penalty-phase trial but warned: "make no mistake" -- Tsarnaev "will spend his remaining days locked up in prison."

"A core promise of our criminal-justice system is that even the very worst among us deserves to be fairly tried and lawfully punished," the court held.

The Trump administration asked the Supreme Court to step in and reinstate the original sentence, a request that the Biden administration renewed, calling Tsarnaev a "radical jihadist bent on killing Americans" who had been convicted of "one of the "worst acts of terrorism on United States soil since September 11th, 2001."

Ginger Anders, a lawyer for Tsarnaev, told the justices there is no dispute that the bombings were a "grievous and shocking act of terrorism" but that the lower court had made two "serious errors" that compromised safeguards needed to ensure that her client received an appropriate penalty.

During the guilt phase of the trial, the lawyers emphasized that Tsarnaev had participated only under his brother's influence. Anders also said the district court had violated the Eighth Amendment and federal law by excluding evidence she said would show that Tamerlan Tsarnaev may have been linked to three murders as an act of jihad in 2011. She said the evidence could have been used to further make the case that it was Tamerlan Tsarnaev, not his brother, who had taken the lead in the bombing and that he had unusual sway over her client.

"That is precisely the kind of evidence that a capital sentencing jury must consider if it is to fulfill its constitutional responsibility to render a reasoned moral response to the defendant and his crime," Anders wrote.

She also took issue with the fact that the district court had refused to ask prospective jurors a question that is normally asked in high-profile cases: "what they remembered hearing about the case."

"The court's refusal to elicit basic information essential to evaluating jurors' claims of impartiality improperly left jurors to be the judges of their own fitness to serve," Anders argued.

It is unclear whether, even if Tsarnaev's death penalty is reinstated, if he would actually be put to death, given the Biden administration's opposition to the federal death penalty.

The Biden administration Justice Department said that while Tsarnaev's lawyers had sought to compel discovery about the 2011 murders, they remain "unsolved" and the lower court judge had said there was insufficient evidence to describe Tamerlan Tsarnaev's true role in the crime to the jury.

Regarding the jury pool, the Justice Department told the justices that the court had summoned an expanded pool, which it screened with a lengthy questionnaire that included multiple questions about pretrial publicity. "

"This court should reverse the decision below and put this case back on track toward a just conclusion," acting Solicitor General Elizabeth Prelogar told the court.

She said that "pretrial publicity -- even pervasive, adverse publicity -- does not inevitably lead to an unfair trial."

Prelogar said the district court had conducted a thorough process in choosing prospective jurors that spanned "21 court days and nearly 4,000 transcript pages."

Over the years, survivors and family members have split on whether Tsarnaev should get the death penalty. In 2015, Bill and Denise Richard penned an op-ed for The Boston Globe after losing their 8-year-old son, Martin. "We know the government has its reasons for seeking the death penalty, but the continued pursuit of that punishment could bring years of appeals and prolong reliving the most painful day of our lives," the Richards wrote.

Jennifer Kauffman said she was watching the race when the first bomb detonated and she suffered hearing loss, heart arrhythmia, internal bruising and swelling. She said she is against allowing another penalty phase to proceed.

"I know there are some people who do not agree with me and that is okay," she told the Globe. "I believe we all have the right to speak up, share our voices, and we each have the freedom to speak our truths even though we may disagree. I only hope we can do so from a place of compassion, kindness and respect for one another."

In a statement to CNN, Mikey Borgard, another survivor, said he thought the lower court was right to overturn the death penalty. "It identified serious problems regarding jury selection and exclusion of crucial mitigation evidence," he said.

He also called the death penalty "barbaric." "I cannot bear the thought of a human life extinguished on my behalf," he said.

But Helen Zhao, the aunt of victim Lingzi Lu, said the court "should not have overturned the verdict." She said she hopes the "next one will come to the same verdict" because "if we give up, basically we lost to him."

This story has been updated with the court's oral arguments Wednesday.

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