US President Joe Biden on Monday commuted the death sentences of 37 of 40 federal inmates, taking action ahead of the return of Donald Trump who oversaw a sweeping number of lethal injections during his first term.

With less than a month left in office, Biden had faced growing calls from death penalty opponents to commute the sentences of those on death row to life in prison without parole, which the 37 will now serve.

The move leaves only a handful of high-profile killers who acted out of hate or terrorism facing the federal death penalty - for which there has been a moratorium under Biden.

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

"I am commuting the sentences of 37 of the 40 individuals on federal death row to life sentences without the possibility of parole," he said.

The three inmates who will remain on federal death row include Dzhokhar Tsarnaev, who helped carry out the 2013 Boston Marathon bombing, and Dylann Roof, an avowed white supremacist who in 2015 shot and killed nine Black churchgoers in Charleston, South Carolina.

Robert Bowers, who killed 11 Jewish worshippers during a 2018 mass shooting at the Tree of Life synagogue in Pittsburgh, will also remain on death row.

Those commuted included nine people convicted of murdering fellow prisoners, four for murders committed during bank robberies and one who killed a prison guard.

"Make no mistake: I condemn these murderers, grieve for the victims of their despicable acts, and ache for all the families who have suffered unimaginable and irreparable loss," Biden said.

"But guided by my conscience and my experience...I am more convinced than ever that we must stop the use of the death penalty at the federal level," he added.

Trump death penalty expansion

Biden campaigned for the White House as an opponent of the death penalty, and the Justice Department issued a moratorium on its use at the federal level after he became president.

During his reelection campaign, Trump spoke frequently of expanding the use of capital punishment to include migrants who kill American citizens and drug and human traffickers.

There had been no federal inmates put to death in the United States since 2003 until Trump resumed federal executions in July 2020.

He oversaw 13 by lethal injection during his final six months in power, more than any US leader in 120 years.

The last federal execution - which was carried out by lethal injection at a prison in Terre Haute, Indiana - took place on January 16, 2021, four days before Trump left office.

The death penalty has been abolished in 23 of the 50 US states, while six others - Arizona, California, Ohio, Oregon, Pennsylvania and Tennessee - have moratoriums in place.

In 2024, there have been 25 executions in the United States, all at the state level.

AFP