In United States v. Tsarnaev, the Supreme Court considered whether a federal district court had properly denied Dzhokhar Tsarnaev’s motion to vacate his convictions and death sentence for his role in the 2013 Boston Marathon bombing. The Court held that the district court did not err when it declined to grant relief on any of Tsarnaev's claims, including those related to alleged juror misconduct during jury selection and ineffective assistance of counsel at sentencing. In its opinion, the Court noted that while some jurors may have failed to disclose their prior knowledge about the case or potential biases they harbored against Tsarnaev, there was no evidence that this information would have changed how these jurors voted or otherwise affected their impartiality as required by law. Additionally, although defense counsel made mistakes during sentencing proceedings—including failing to present certain mitigating evidence—the Court found that such errors were unlikely enough to make a difference in light of all other factors presented at trial. Thus, despite numerous challenges raised by Tsarneav's attorneys over several years since he was convicted and sentenced in 2015, none were successful before either lower courts or now before SCOTUS itself; thus affirming both his conviction and death sentence handed down from below

In the dissenting opinion of United States v. Tsarnaev, Justice Sotomayor argued that the majority opinion was wrong to uphold the death penalty for Dzhokhar Tsarnaev, the Boston Marathon bomber. She argued that the jury was not given the opportunity to consider mitigating evidence that could have resulted in a lesser sentence. She argued that the jury was not given the opportunity to consider Tsarnaev’s age, his family’s history of mental illness, and the fact that he was influenced by his older brother. She argued that the jury should have been given the opportunity to consider these factors and that the death penalty was too harsh a punishment for Tsarnaev. She argued that the death penalty should only be used in the most extreme cases and that this case did not meet that standard. She argued that the death penalty should not be used as a form of retribution, but rather as a way to protect society from future harm. She argued that the death penalty should not be used in cases where the defendant is not a danger to society and that Tsarnaev did not meet that standard. She argued that the death penalty should not be used as a form of revenge and that the majority opinion was wrong to uphold the death penalty in this case.