Alabama intends to carry out the first known execution by nitrogen gas this week, when it’s scheduled to put to death Kenneth Smith some 14 months after failing to carry out his capital punishment by lethal injection.
But little is known about how the method, nitrogen hypoxia, will be carried out?during a 30-hour execution window?Thursday?into?Friday, as?the state’s published protocol bears redactions that experts say shield key details from public scrutiny.?The state, in court records, indicated the redactions were made to maintain security.
“This is a protocol that has been created out of whole cloth,” said Robin Maher, executive director of the Death Penalty Information Center, a non-profit that’s critical of how capital punishment is administered in the United States but does not take a stance on it.
“There’s no precedent for it,” she told CNN. “There’s no testing of this procedure. No one knows how it’s going to occur.”
Amid the uncertainty, Smith and his lawyers – along with experts from the United States to the United Nations – have questioned whether potential complications from the nitrogen gas procedure could lead to excessive pain or even torture for?the inmate who previously asked to be put to death in this way.
“It’s not that nitrogen gas won’t kill you,” Dr. Joel Zivot, an associate professor of anesthesiology and surgery at Emory University, told CNN. “But will it kill you in a way that would comport with the Constitutional requirement that it not be cruel and it not be torture?”
Alabama is one of just three states, along with Oklahoma and Mississippi, that have approved use of nitrogen gas to carry out death sentences. But none has used it, and only Alabama has outlined a protocol.
While some US states decades ago used lethal gas to execute prisoners, the use of nitrogen would be new: In theory, it involves replacing the air breathed by an inmate with 100% nitrogen, depriving the body of the oxygen it needs to survive. Such displacement would lead to a painless death, according to the method’s proponents, who cite nitrogen’s role in deadly industrial accidents or suicides.
But those environments are different than an execution, said Zivot, who added he fears Alabama’s attempt could go awry and prompt myriad potential complications, such as causing Smith to have a seizure or vomit into the mask delivering the nitrogen, causing him to choke.
Meanwhile, though secrecy over the death penalty is not uncommon – many states keep private certain details of their execution procedures – experts say this moment is also troubling because Alabama in 2022 hosted three?lethal injections, including Smith’s, that critics deemed “botched” because they deviated from protocol.
“Given the history that Alabama has, with so many botched executions, it seems hard to believe that they would be pivoting to a new, untested and risky procedure,” Maher?said.
For its part, though, Alabama this week is “ready to go,” with the nitrogen hypoxia?execution of Smith, its Republican governor told CNN in a statement:
“This method has been thoroughly vetted, and both the Alabama Department of Corrections and the Attorney General’s Office have indicated it is ready to go,” said Gov. Kay Ivey, whose office declined to provide an unredacted copy of the nitrogen hypoxia execution protocol or respond to CNN’s questions about experts’ concerns over it.
The murder of Elizabeth Sennett
Smith was sentenced to death for his role in the 1988 murder for hire of Elizabeth Sennett. According to court records, her husband, minister Charles Sennett, hired someone who?hired two others, including Smith, to kill his wife and make it look like a burglary.
Sennett, who court records say was having an affair and had taken out an insurance policy on his wife, killed himself a week after her murder as investigators’ focus turned to him. Smith was eventually arrested after investigators searched his home and found the Sennetts’ VCR.
Smith had expressed a desire to be executed by nitrogen hypoxia before Alabama tried to put him to death in November 2022 using lethal injection. The state aborted that attempt because officials could not set an intravenous line before the execution warrant expired.
He shared his wish again after that attempt – then reversed course in August, when the state suddenly agreed to use the method and released the heavily redacted protocol. Smith then challenged the protocol, claiming it left him at risk of “superadded pain,” could cause him to have a stroke or could leave him in a vegetative state if it fails, court records show.
A federal judge’s ruling this month cleared the way for Alabama to proceed, finding there was “simply not enough evidence to find” the protocol would cause Smith “superadded pain.” And while the judge acknowledged the “heavily redacted” protocol maintained the Department of Corrections’ “familiar veil of secrecy over its capital punishment procedures,” he also noted the state had provided Smith’s team an unredacted protocol. Further details, including the specific mask that will be used, were revealed in oral arguments last month.
The ruling?placed Alabama “an important step closer to holding Kenneth Smith accountable” for Sennett’s killing, state Attorney General Steve Marshall said in a statement the day of the ruling. “Smith has avoided his lawful death sentence for over 35 years, but the court’s rejection …?of Smith’s speculative claims removes an obstacle to finally seeing justice done.”
“Now that the State is prepared to give Smith what he asked for, he objects,” Marshall’s office told CNN this week in a separate statement, which also pointed out that an advocate for assisted suicide later called as an expert witness by Smith and his attorneys posted on X in September that nitrogen hypoxia was “not ‘cruel & unusual’” but “fast” and “effective.”
That expert subsequently testified in Smith’s case to the potential for complications to arise during the nitrogen hypoxia execution, saying he could not exclude the possibility Smith would be left with permanent brain damage, according to the judge’s ruling.
And still in the case, litigation continues: Last week, Smith’s attorneys asked the US Supreme Court for a stay of execution, asserting a second attempt to execute him would constitute cruel and unusual punishment.
For their part, Elizabeth Sennett’s sons plan to be present for Smith’s execution, finally here after 35 years, they told CNN affiliate WAFF.
“The man’s been in prison right at twice as long as we knew our mom,” Mike Sennett said.
Death by nitrogen gas
The origins of nitrogen hypoxia as an execution method trace in most sources to a 1995 article in National Review, though it’s gained increasing traction in recent years as states struggle to implement lethal injection, according to Deborah Denno, a professor at Fordham Law School who has studied the death penalty for decades.
Since its inception 40 years ago, lethal injection has become by far the most prominent method of execution for the US government and the 27 states that still have the death penalty. But beginning around 2009, states began losing access to the drugs long used to carry it out, leading to use of alternative drugs that have led to a “surge in problems with lethal injection,” Denno told CNN.
That’s created a moment ripe for the rise of another method, she indicated, describing the circumstances as a pattern that has been repeated for more than a century and a half, such as?when electrocution – conceived as more humane than hanging – was sidelined following grisly botches.
“It was when states are pushed into a corner and they are desperate, it’s at that point, they come up with a new method of execution,” Denno said.
Oklahoma was first to adopt nitrogen gas as an execution method in 2015 as a backup if lethal injection were ever found unconstitutional or “otherwise unavailable.” The legislation’s passage, per Denno, was based in part on an unpublished paper by three academics at East Central University, who concluded nitrogen hypoxia could “assure a quick and painless death.”
Then-Oklahoma Corrections Department Director Joe Allbaugh echoed that in 2018, when officials said they intended to move forward with nitrogen gas executions. “After a couple breaths,” Allbaugh said at the time, “the individual loses consciousness, doesn’t feel anything.”
Alabama adopted nitrogen hypoxia that same year, with the state lawmaker who sponsored the legislation telling AL.com he believed it would be more humane than lethal injection.
UN experts call on Alabama to halt execution
Many others, including Zivot, however, remain skeptical of nitrogen hypoxia, with the anesthesiologist pointing to several potential complications, including the risk that the nitrogen causes Smith to have a seizure, which could make him vomit into the mask and then choke.
Zivot also raised the possibility of an ineffective seal on the mask, allowing nitrogen to leak out, prolonging the execution or leaving Smith severely injured. A leak could also present a risk to others, like witnesses, corrections officials or Smith’s spiritual adviser, Zivot said. Indeed, the adviser had to sign a waiver acknowledging he could be exposed to the gas, NPR reported.
“Alabama, again, has no idea whether this will happen, whether it won’t happen, what they’ll do about it,” he said. “But these are all kind of concerns, you know, with this particular method of execution.”
Those concerns are shared by parties far beyond Alabama: Earlier this month, United Nations experts “expressed alarm” over Smith’s looming execution, saying in a news release, “We are concerned that nitrogen hypoxia would result in a painful and humiliating death.”
The UN High Commissioner for Human Rights almost two weeks later called on Alabama to halt the execution, saying it “could amount to torture or other cruel, inhuman or degrading treatment or punishment under international human rights law.”
While those sentenced to death are often convicted of particularly heinous crimes and deemed the “worst of the worst,” the Constitution still protects them, said Maher, the Death Penalty Information Center director.
“The people that we have placed in prisons and jails are still human beings who are deserving of the same kind of dignity that we would demand for ourselves and anyone that we love,” she said. “They are entitled to the protections of the Constitution the same as anyone else in this country. And they certainly should be free from being tortured or inhumanely executed.”
How the death penalty is used “says a lot about us as a society,” she added, noting secrecy about it “increases the risk of problems,” leading to more botched executions.
“The fact that this incredibly important function, which is probably the biggest use of government power, the details of which are being kept from the public,” she said, “that raises a lot of questions about whether this is the right thing to do.”