NEW YORK (REUTERS) - Boston Marathon bomber Dzhohkar Tsarnaev was sentenced to death on Friday. But his execution may not happen for decades - if ever.
A lengthy appellate process, an effective moratorium on federal executions and declining support among Americans for capital punishment all suggest that Tsarnaev's death by lethal injection is far from a sure thing, according to death penalty experts.
Instead, it may end as a purely symbolic judgment.
"With every passing year, the likelihood of execution will diminish," said Deborah Denno, a law professor at Fordham University who has studied capital punishment.
That said, many of the issues that typically draw criticisms of death penalty sentences, such as inadequate legal counsel and post-conviction exonerations, are not present in the Tsarnaev case.
His legal team included one of the most respected death penalty lawyers in the country, Judy Clarke, and she did not attempt to argue his innocence at trial.
The absence of those criticisms, along with the sheer horror of the crime, could make Tsarnaev the "perfect test case" for the future of capital punishment, said Douglas Berman, a law professor at Ohio State University who specialises in federal sentencing.
"I think it's 50-50," he said. "This could be the case that people have in mind when they say we reserve the death penalty for the worst of the worst."
Tsarnaev was sentenced to death by a federal jury for helping carry out the 2013 attack that killed three people and wounded 264 others in the crowds at the finish line of the Boston Marathon. The same jury found Tsarnaev guilty last month in the bombing, which was one of the highest-profile attacks on US soil since Sept 11, 2001.
While Massachusetts has banned the death penalty, Tsarnaev was convicted of federal crimes, which can carry a death sentence under US law.
- Lethal injection controversy -
The use of lethal injection has come under intense scrutiny since an Oklahoma execution went awry in April 2014, leaving convicted murderer Clayton Lockett twisting on the gurney after prison staff failed to place the intravenous line properly.
The US Supreme Court is currently considering the constitutionality of Oklahoma's three-drug process, and several other states that use similar methods have seen their executions put on hold while they await the court's ruling.
Meanwhile, President Barack Obama has ordered a review of the government's use of lethal injection, effectively implementing a moratorium on federal executions, while saying there are "significant questions" about whether capital punishment is applied fairly.
Even before the problems with lethal injections made headlines, however, US public support for the death penalty was declining, according to Austin Sarat, a political science professor at Amherst College and the author of "Gruesome Spectacles: Botched Executions and America's Death Penalty."
"We're in a period of national reconsideration of capital punishment," he said. "I don't think this case will derail that in any shape or form."
- Federal executions rare -
At the federal level, only three defendants out of the 74 sentenced to death since 1988 have been executed, according to the Death Penalty Information Centre. The first was the Oklahoma City bomber Timothy McVeigh, who killed 168 people in a truck bombing in 1995 and was executed in 2001 after dropping his appeal.
Frank Zimring, a law professor at the University of California in Berkeley, said the low number reflects not only a complicated and long appellate process but a growing distaste for carrying out death sentences.
"Nobody's anxious to have federal executions," he said, noting that the last occurred in 2003.
Some experts said the Obama administration's two-pronged approach - pursuing a death sentence even as it reviews the use of capital punishment - shows it was more interested in securing the "symbolic" victory of a death sentence than in carrying it out.
"There's a lot of evidence that what Americans want are death sentences, not executions," Sarat said.