President Biden announced Monday that he had commuted the sentences of 37 of the current 40 federal death row inmates to life in prison without the possibility of parole.

“These commutations are consistent with the moratorium my administration has placed on federal executions in cases other than terrorism and hate-motivated mass murder,” Biden said in a statement.

Consistent with this rationale, Biden did not change the death sentences for three notorious federal inmates: Dylann Roof, Dzhokhar Tsarnaev and Robert Bowers.

Here’s a look at the three people Biden didn’t spare and the motivation behind his decision.

The three that remain

Each of the three federal death row inmates whose sentences Biden did not commute fit into the categories laid out in the president’s statement – cases of terrorism or “hate-motivated mass murder.”

Dylan Roof

On June 17, 2015, Roof, a white supremacist from South Carolina, opened fire during a Bible study at the Emanuel African Methodist Epispocal Church in Charleston, killing nine black Americans and wounding another. He declared his hatred of black people on a website registered in his name.

Dzhokhar Tsarnaev

Tsarnaev, an American citizen of Chechen descent, along with his brother Tamerlan, planned and carried out the terrorist attack on the Boston Marathon on April 15, 2013, which killed three people and injured 264 others. Although his brother was killed in a shootout with police four days later, Dzhokhar survived. He told police that the bombing was in retaliation for the deaths of Muslims caused by U.S. military action.

Robert Bowers

During Sabbath services on the morning of October 27, 2018, white nationalist Robert Bowers carried out the deadliest attack on Jews in U.S. history at the Tree of Life Congregation in Pittsburgh. He opened fire with a semi-automatic AR-15 weapon, killing 11 people and wounding another six worshipers.

Biden’s motivation

A critic of the death penalty, Biden was the first US president to openly oppose the death penalty. In 2020, he stated on his campaign website that he would “work to pass legislation abolishing the death penalty at the federal level and encourage states to follow the federal government’s lead,” the Associated Press reported.

In 2021, the Biden administration announced a pause on the federal death penalty to allow the Justice Department to investigate how it is imposed. This moratorium ended the practice during Biden’s term.

On Monday, Biden stated, “Guided by my conscience and experience as a public defender, chairman of the Senate Judiciary Committee, vice president and now president, I am more convinced than ever that we must stop the use of the death penalty at the federal level.”

A practicing Catholic, Biden’s decision was praised by the U.S. Conference of Catholic Bishops, which called the commutations “a step closer to building a culture of life,” and by groups that have long argued that black Americans are disproportionately given the death penalty.

Biden also made it clear in his statement that Donald Trump’s return to the White House helped justify his decision to largely clear out death row.

“In good conscience, I cannot allow a new administration to resume the executions I stopped,” he wrote.

During Trump’s first term, his administration ended a 17-year pause in federal executions and ultimately executed 13 federal prisoners. While that number was the highest of any administration in modern history, Trump has since campaigned on promises to expand the death penalty to drug dealers.

But now only three people remain on federal death row. Given the time it takes to convict death sentences and the fact that the average appeals process takes 966 days, Trump may not be able to execute more federal prisoners in his second term than in his first.

Commutation vs. pardon

Biden’s commutation of federal death row inmates in no way exonerates those convicted of murder, but the action spares them from execution.

Unlike pardons, which grant a complete forgiveness of a crime and restore full citizenship rights, commutations represent a reduction in sentence. In this case, the reduction consists of serving a life sentence rather than the prospect of execution.

Roof, Tsarnaev and Bowers could still be executed.