The lethal injection chamber at the Louisiana State Penitentiary, known as Angola. Across the country, people in prison are fighting increasingly uphill battles to prove that the ways states carry out executions violate the Constitution. (Photo by William F. Campbell/Getty Images)
Justice Sonia Sotomayor broke the fourth wall in her Oct. 23 opinion dissenting from the U.S. Supreme Court's refusal to stop Alabama's nitrogen gas execution of Anthony Boyd, speaking directly to the reader.
"Take out your phone, go to the clock app, and find the stopwatch. Click start," the justice said, then asked readers to stop the clock after four long minutes in which the mind starts to wander.
"Now imagine for that entire time, you are suffocating. You want to breathe; you have to breathe. But you are strapped to a gurney with a mask on your face pumping your lungs with nitrogen gas. Your mind knows that the gas will kill you. But your body keeps telling you to breathe," Justice Sotomayor said. "That is what awaits Anthony Boyd tonight. For two to four minutes, Boyd will remain conscious while the State of Alabama kills him in this way."
Later that evening, Boyd was put to death. News media witnesses saw Boyd thrashing against his restraints, rolling his eyes back and lifting his legs from the gurney in an execution that took nearly 40 minutes.
Justice Sotomayor's scathing dissent, in which she was joined by Justices Elena Kagan and Kentanji Brown Jackson, was a pointed volley in the legal battles over the methods states use to put people to death.
In sprawling, piecemeal litigation in several states, people on death row are challenging execution methods as unconstitutional, arguing such methods would cause unnecessary suffering. So far, those challenges have largely failed.
John H. Blume, a professor at Cornell University Law School who has litigated some of these challenges, told Law360 that neither the U.S. Supreme Court nor state high courts have shown much interest in using judicial power to stop executions on these constitutional grounds.
"We haven't seen much of what I would call judicial courage from state courts on any of this," he said.
In February 2024, Blume unsuccessfully argued a case before the South Carolina Supreme Court on behalf of four people facing executions. The plaintiffs challenged a state law authorizing three alternative methods of execution — electrocution, firing squad and lethal injection — as violating the state constitution.
Enacted in 2021, the state law, Section 24-3-530, adopted the electric chair as South Carolina's default execution method, and allowed people facing execution to choose the other two.
While South Carolina adopted lethal injection in 1995, the state has had to look for alternatives because of its inability to obtain the necessary drugs over the past 15 years. Lawmakers also declined to pass legislation that would have facilitated getting the drugs, resulting in a de facto pause in executions.
In a firing squad execution, bullets fired into a person are supposed to destroy their heart nearly instantaneously, stopping the circulation of blood to the brain. During an electrocution, two rounds of high-voltage and one round of low-voltage current are sent through a person's body, causing the heart's rhythm to be extremely fast and irregular and disrupting respiration and circulation until death.
The South Carolina lawsuit culminated in a bench trial in August 2022 before state Circuit Judge Jocelyn Newman. The four plaintiffs — Freddie Eugene Owens, Brad Keith Sigmon, Gary DuBose Terry and Richard Bernard Moore — objected to each method as violating the state constitution's prohibition on "cruel or unusual or corporal punishment," a broader protection than the one provided by the U.S. Constitution, which forbids "cruel and unusual punishments."
Judge Newman agreed with the plaintiffs, issuing an order finding electrocution and the firing squad unconstitutional. The judge wrote that South Carolina lawmakers had "turned back the clock" and "ignored advances in scientific research and evolving standards of humanity and decency."
To support their constitutional claims, the plaintiffs summoned expert witnesses who testified about the effects on the human body of electrocution and being shot by bullets.
Dr. Jonathan Arden, a forensic pathologist, testified that gunshot wounds to the chest cause extensive damage, including fractures of the ribs and sternum. Arden said that when the heart ceases delivering blood to the brain after being shot, a person would remain sensate — or able to perceive through the senses — for at least 15 seconds, during which they might experience excruciating pain. But if the heart is not completely disabled, the sensation and the pain could last longer.
Arden also testified about severe injuries caused by electrocution, describing the effects of electrical and thermal burns on tissue and organs as "the equivalent of cooking." Arden said that if a person were still conscious during the electrocution, they would experience "horrific pain" because of the burns, according to an account of the testimony contained in Judge Newman's order.
Testifying for the state, Dr. Ronald Wright, a forensic pathologist, said that when a person is electrocuted with very high-voltage current, they are immediately rendered unconscious and cannot regain consciousness because their brain cells have been damaged. Even if that doesn't happen, Wright said, a person will die quickly because the human heart violently contracts right after the current is discharged.
"If I had been sentenced to die, that would be my choice because it doesn't hurt," Wright said during the testimony, though he was unable to explain electrocutions during which people being executed breathed, moved and screamed after the application of electric current, according to the order.
Judge Newman ultimately found that the effect of the firing squad "constitutes torture" and that the method is cruel, unusual and corporal — in this context meaning that it mutilates the human body — and thus in violation of the state constitution.
The judge reached a similar conclusion about the electric chair, saying that because the human skull is significantly more resistant to electrical current than other parts of the body, not all of the current applied in the first two rounds will enter a person's brain, increasing the likelihood that they would still be conscious during the last application of current, which causes more pain.
"This creates a risk that an inmate will remain conscious and sensate while he is burned, bruised, and suffocated," Judge Newman wrote.
But in July 2024, the state Supreme Court overturned that decision. The court found that the 2021 statute "as a whole is constitutional" because it guarantees every person facing execution at least one constitutional method, and allows the individual, not the state, to choose among them. The court held that the availability of multiple options means no one could ever be executed by a method they consider more painful than another available alternative.
"If any condemned inmate in this State believes that any one of the three methods of execution now set forth in section 24-3-530 is unconstitutional, he has two other constitutional choices," the court said.
Sigmon was executed by a firing squad on March 7. Owens and Moore were put to death last year by lethal injection.
A Legal Standard That Is "Out of Reach"
Over the last two decades, litigating how states kill has become less about proving a method is cruel and more about clearing an ever-rising legal bar.
Ruling in Baze v. Rees in 2008, the U.S. Supreme Court built a framework, later sharpened in 2015's Glossip v. Gross, and 2019's Bucklew v. Precythe, that requires petitioners to clear two high hurdles.
In Baze, the court made clear that executions can involve pain, and that only a "substantial risk of severe pain" as compared to the available alternative execution methods violates the Eighth Amendment.
In Glossip, the court said that to prevail in a method of execution challenge, a petitioner must also identify an alternative method that is "feasible, readily implemented" and would significantly reduce the risk of severe pain.
And in Bucklew, the Supreme Court required federal courts to focus on the prisoner's risk of severe pain and expanded the state's ability to reject alternatives, setting an even higher bar for people challenging executions. That ruling directed courts to distinguish between physical pain, which matters in a constitutional claim, and psychological terror or fear, which generally does not.
States, on the other hand, can reject alternative methods for reasons such as logistics, availability and security. Also, states are not required to adopt untried and untested execution methods.
Robin Maher, executive director of the Death Penalty Information Center, said the legal standard set by the Supreme Court has effectively shut down meaningful review of execution methods under the Eighth Amendment.
"Where we used to be in a conversation about what is cruel and unusual under the amendment, we are now looking at a standard that is so very high and out of reach that those claims are largely futile," she said. "We never even get to the question, because no one can meet the standard to even bring the claim and the United States Supreme Court has said it will not look at those cases."
Some legal scholars say the court's approach also ignores the basic power imbalance between people facing execution and the states seeking to kill them.
Meghan Ryan, a professor at Southern Methodist University's Dedman School of Law, said that by placing the burden on petitioners, the court is stacking the deck against challenges to methods of execution, which require the work of skillful attorneys and expert testimony.
"It's, I think, difficult to put that onus on someone who's stuck in prison to try to figure this out and have the expertise, whereas the government has all the resources at its disposal," Ryan said.
Despite botched executions involving lethal injection, firing squad and nitrogen hypoxia across several states during the last decade, the Supreme Court has refused to step in.
"They've said, very clearly, 'It's not our business to be interfering in what the states choose to do,'" Maher said.
As a result, more lawyers have begun shifting their efforts toward state constitutions, which sometimes offer broader protections — though, as South Carolina's high court showed, state courts are not necessarily more receptive.
Challenging an Untested Method
In June 2018, after Alabama lawmakers authorized nitrogen hypoxia as a method of execution, the state gave people on death row 30 days to decide whether to opt into the new, untested method, or remain with lethal injection, the state's standard practice. At the time, the state had not yet established a protocol for nitrogen hypoxia executions.
Boyd, who was convicted for his role in the 1993 kidnapping and murder of Gregory Huguley and sentenced to death after a jury recommended capital punishment in a 10-2 vote, was among those who chose nitrogen.
A string of botched lethal injections across the country in the years leading up to that moment weighed heavily on Boyd. This included the failed February 2018 execution of Doyle Lee Hamm in Alabama, in which Hamm was strapped to a gurney for 2½ hours as a team repeatedly tried and failed to find a vein. Those cases convinced Boyd that nitrogen gas, which officials claimed causes a person to lose consciousness and die "within minutes," was the option most likely to spare him the greatest amount of suffering.
But after Alabama began to perform executions with nitrogen gas in January 2024, when the state executed Kenneth Eugene Smith, Boyd changed his mind.
Witnesses to Smith's execution saw him convulse and struggle against his restraints for several minutes after the gas began flowing into his mask. Some described him as shaking violently, gasping for air and clenching his fists.
"We didn't see somebody go unconscious in 30 seconds. What we saw was minutes of someone struggling for his life," Jeff Hood, Smith's spiritual adviser who was in the execution chamber with him, told reporters afterward. "We saw minutes of someone heaving back and forth. We saw spit. We saw all sorts of stuff develop from his mask."
On July 16, Boyd filed a suit asking a federal court to prevent the state from using nitrogen hypoxia to kill him. Boyd argued that the method violated the Eighth Amendment because it would cause him to experience extreme pain and terror from being deprived of oxygen, which he described as "conscious suffocation."
By the time he lodged his challenge, five more people had been executed with nitrogen gas: four in Alabama and one, Jessie Hoffman Jr., in Louisiana, the first time that state had used the method.
All those executions were marked by signs of struggle by the person being executed, who either shook while restrained on the gurney, clenched their hands, pulled their arms against their restraints and, in some cases, displayed signs of anxiety and fear including rapid eye movement and pupil dilation, Boyd said in his complaint.
Boyd proposed three alternative methods: a firing squad, hanging — which he later dropped as an option — and medical aid in dying, consisting of a potent mix of sedative and paralytic drugs that some states use in medically assisted deaths.
But on Oct. 9, two weeks before Boyd's scheduled execution, U.S. District Judge Emily M. Marks of the Middle District of Alabama denied his motion for a preliminary injunction.
The judge held that Boyd's claims weren't likely to succeed on the merits, writing in her opinion that he had failed the legal tests established by the Supreme Court in Bucklew, Baze and Glossip. Judge Marks also said Boyd waited too long to bring the lawsuit, which he filed nearly two years after Alabama released its nitrogen protocol in August 2023.
In her opinion, Judge Marks referred to the Supreme Court rulings, saying the Eighth Amendment does not require a painless death and that psychological distress is inherent in all executions.
A three-judge panel of the Eleventh Circuit upheld the ruling, finding that the district court had correctly applied the Supreme Court precedent.
How Long and How Painful?
In challenges to execution methods, two questions dominate: How long will death take, and will the person be able to feel what is happening to them during that time?
Cornell's Blume said that constitutionally, the amount of time required to kill a person is less important than whether they are insensate, meaning they can't feel anything, including pain.
"It's not just the amount of time," he said. "The issue is the time, and is the person conscious or not?"
Blume noted that even in firing squad executions, which some states claim are swift, the initial shots do not render a person unconscious. The state's assumption is that the heart will be obliterated instantly, cutting off blood supply to the brain so rapidly that consciousness fades within seconds. But when shots miss or fail to destroy the heart, he said, the person could be conscious for significantly longer.
"It's going to hurt like hell, and it's going to shatter their rib cages," he said. "But the question is: How long before all the blood bleeds out?"
The April 11 firing squad execution of Mikal Deen Mahdi in South Carolina provides a case in point. An autopsy report showed that Mahdi had only two gunshot wounds to his chest, indicating that one of the three riflemen tasked with the execution missed the target completely. But the report also showed that the shooters who hit him missed his heart, causing a slower death than anticipated.
"He clearly was alive for significantly longer," Blume said.
South Carolina's firing squad protocol has been criticized by experts in other litigation for relying on too few shooters. Utah, another state that uses firing squads, uses five shooters.
Mahdi's execution, the experts said, underscored precisely why Judge Newman had originally found the method "corporal" and "torture" before the state Supreme Court reversed her. No other person sentenced to death in South Carolina has chosen the firing squad since Mahdi's execution.
Pain and timing also played a significant role in the litigation brought in Alabama federal court by Boyd.
Judge Marks' ruling dismissing the suit turned largely on two related questions: How long would Boyd remain conscious under Alabama's nitrogen hypoxia protocol, and what type of suffering, physical or psychological, would he experience during that window?
The court's analysis focused on how long a person remains conscious after oxygen is withdrawn, and whether the deprivation is long enough — and distressing enough — to violate the Eighth Amendment.
Expert witnesses in Boyd's case disagreed on how long that consciousness period would last. Dr. Joseph Antognini, an anesthesiologist testifying for the state, said unconsciousness would come in 35 to 40 seconds, possibly sooner. But Dr. Philip E. Bickler, who testified as Boyd's expert, said it would take about two minutes for a person breathing normally to fall unconscious, a time that could be even longer if they breath shallowly or hold their breath.
Judge Marks found that even taking the facts in the light most favorable to Boyd, he could not meet the legal standard. The court acknowledged that a "primal" drive to breathe would trigger a "terror response" because a person being executed does not want to die, but concluded that it "is true for virtually all executions and does not implicate the Eighth Amendment."
Scientific Study Falls Short
Experts say the scientific study of execution methods is thin and courts struggle to grasp important nuances within it, a gap that scholars say undermines the entire legal framework governing the Eighth Amendment.
Courts are asked to weigh the "substantial risk" of pain associated with a given execution method, yet no meaningful body of science needed to make such judgments exist.
Deborah W. Denno, a professor at Fordham University School of Law who has studied execution protocols for more than three decades and whose writings have been cited by the Supreme Court, said the core problem is that the United States has never developed a real scientific foundation for its methods of execution.
"We just don't know very much on how to kill people," she said. "In this kind of context — executing people as a punishment — it's much more difficult than people realize."
Executions, she explained, aren't designed with scientific rigor because modern medicine focuses on preserving life, not ending it, and because ethical rules preclude the kind of testing that would normally precede the use of techniques that affect a human body so drastically.
Historically, execution methods like electrocution were tested on animals — dogs or even elephants — but that approach is legally and ethically impossible today.
Denno noted that the newest execution method, nitrogen hypoxia, was introduced without even that rudimentary level of evaluation, as "an act of desperation." States turned to it not because of evidence suggesting it was humane, but because lethal injection drugs became difficult to acquire, she said.
"Nitrogen hypoxia has probably been the least examined method of execution," she said.
The scientific vacuum extends to pain, the central concept in modern execution litigation. Neuroscience offers little clarity about what pain looks like in a dying brain or how to measure it.
Ryan, the SMU professor, said that in medicine, patients self-report pain because clinicians have no objective way to quantify it. Courts, she said, face the same limitation, and so judges typically end up relying on witness descriptions of botched executions — things like body movements, gasping and vomiting — rather than on scientifically validated indicators of suffering.
"We don't know a whole lot about pain," she said. "We don't even have any means by which to measure it."
Yet the Supreme Court's modern doctrine demands a precise accounting of pain as part of the framework established under Baze, Glossip and Bucklew. Those cases moved away from the prior "evolving standards of decency" test that made room for new scientific knowledge.
Ryan noted that as the court turned more conservative starting in President Donald Trump's first term with the addition of Justices Brett Kavanaugh, Neil Gorsuch and Amy Coney Barrett, it has increasingly embraced an originalist framework that looks to 18th-century practices surrounding the application of the death penalty, even though those practices say little about modern physiology or the neuroscience of suffering.
Meaningfully incorporating science to try to answer the question of which execution methods can pass constitutional muster, Ryan said, would require robust factual development at the trial level: expert testimony, autopsies, toxicology reports and detailed analysis of how different mechanisms cause distress.
But that rarely happens, she said; capital defendants usually lack the resources to build such a record, and prosecutors have no incentive to deepen the scientific inquiry. Trials often proceed with a narrow evidentiary base that leaves judges to resolve questions science itself cannot answer, she said.
Even collecting data during executions — for example, monitoring vital signs, measuring brain activity or recording physiological responses — is practically difficult, Ryan said. States restrict who may witness executions and enact secrecy laws to shield protocols, drug sources and staff identities.
"I don't know that they want to do further research on these types of issues," Ryan said. "I would imagine that information would not be good for the government."
A State That Obscures Its Methods
While some states push forward with new execution methods, others are fighting to keep old ones hidden from view.
In Tennessee, a sweeping lawsuit is targeting the secrecy of the state's lethal injection protocol, a challenge that strikes at what one attorney calls a "culture of recklessness and non-compliance" within the state's Department of Correction.
Kelley Henry, a supervising attorney with the Federal Public Defender's Office in Nashville, is leading the suit on behalf of seven men on death row. The case, filed in Tennessee's Chancery Court, is set for trial in April and raises Eighth Amendment and First Amendment claims.
At its core is an allegation that the state has been using execution drugs procured through the so-called gray market, in which medications start in the legitimate medical supply chain but are later diverted and sold without oversight from the U.S. Drug Enforcement Administration. The lawsuit also alleges that officials have repeatedly misled courts and the public about drug testing and potency as well as their failures to comply with their own protocol.
Henry said the challenge grew out of discoveries made three years ago, when lawyers learned the state's Department of Correction had given false testimony about the drugs used in prior executions. According to Henry, the old protocol required the state to test the compounded chemicals before use — tests that, in many cases, never happened. In other cases where testing was performed, the drugs were found not potent enough to be reliable in executions.
"We are trying to get as much information as we can about the drugs that are being used," she said, "because if they are adulterated, cut, poorly stored, poorly handled, not kept at the appropriate temperature during transport, then that poses a problem and a risk for our clients."
She pointed to the 2018 execution by lethal injection of Billy Ray Irick, where witnesses reported visible signs of suffering, and to the case of her former client Byron Black, who during his Aug. 5 lethal injection continued to exhibit movement well past the point when the state's expert said he should have been unconscious.
"Something went wrong in his execution," Henry said. "We're investigating why that happened."
The underlying problem, Henry said, is secrecy. Tennessee's Public Records Act shields the identities of execution participants, and state courts have repeatedly barred defense teams from obtaining information about the individuals and companies involved in sourcing, storing and compounding the drugs used for lethal injections.
Henry said that lack of transparency has allowed violations to go unchecked.
"What we're finding is that lack of accountability is leading to the department's being reckless in the executions, because at the end of the day, the person is dead, and that was the goal, and that's all they care about," she said.
Henry said Tennessee spent $600,000 on execution drugs, creating powerful incentives for illicit suppliers.
"There's a huge market incentive to cut the drugs with something else," she said. "The trend that I'm seeing is the state doubling down on lack of transparency."
--Editing by Orlando Lorenzo and Alanna Weissman.
Have a story idea for Access to Justice? Reach us at accesstojustice@law360.com.
"Take out your phone, go to the clock app, and find the stopwatch. Click start," the justice said, then asked readers to stop the clock after four long minutes in which the mind starts to wander.
"Now imagine for that entire time, you are suffocating. You want to breathe; you have to breathe. But you are strapped to a gurney with a mask on your face pumping your lungs with nitrogen gas. Your mind knows that the gas will kill you. But your body keeps telling you to breathe," Justice Sotomayor said. "That is what awaits Anthony Boyd tonight. For two to four minutes, Boyd will remain conscious while the State of Alabama kills him in this way."
Later that evening, Boyd was put to death. News media witnesses saw Boyd thrashing against his restraints, rolling his eyes back and lifting his legs from the gurney in an execution that took nearly 40 minutes.
Justice Sotomayor's scathing dissent, in which she was joined by Justices Elena Kagan and Kentanji Brown Jackson, was a pointed volley in the legal battles over the methods states use to put people to death.
In sprawling, piecemeal litigation in several states, people on death row are challenging execution methods as unconstitutional, arguing such methods would cause unnecessary suffering. So far, those challenges have largely failed.
John H. Blume, a professor at Cornell University Law School who has litigated some of these challenges, told Law360 that neither the U.S. Supreme Court nor state high courts have shown much interest in using judicial power to stop executions on these constitutional grounds.
"We haven't seen much of what I would call judicial courage from state courts on any of this," he said.
In February 2024, Blume unsuccessfully argued a case before the South Carolina Supreme Court on behalf of four people facing executions. The plaintiffs challenged a state law authorizing three alternative methods of execution — electrocution, firing squad and lethal injection — as violating the state constitution.
Enacted in 2021, the state law, Section 24-3-530, adopted the electric chair as South Carolina's default execution method, and allowed people facing execution to choose the other two.
While South Carolina adopted lethal injection in 1995, the state has had to look for alternatives because of its inability to obtain the necessary drugs over the past 15 years. Lawmakers also declined to pass legislation that would have facilitated getting the drugs, resulting in a de facto pause in executions.
In a firing squad execution, bullets fired into a person are supposed to destroy their heart nearly instantaneously, stopping the circulation of blood to the brain. During an electrocution, two rounds of high-voltage and one round of low-voltage current are sent through a person's body, causing the heart's rhythm to be extremely fast and irregular and disrupting respiration and circulation until death.
The South Carolina lawsuit culminated in a bench trial in August 2022 before state Circuit Judge Jocelyn Newman. The four plaintiffs — Freddie Eugene Owens, Brad Keith Sigmon, Gary DuBose Terry and Richard Bernard Moore — objected to each method as violating the state constitution's prohibition on "cruel or unusual or corporal punishment," a broader protection than the one provided by the U.S. Constitution, which forbids "cruel and unusual punishments."
Judge Newman agreed with the plaintiffs, issuing an order finding electrocution and the firing squad unconstitutional. The judge wrote that South Carolina lawmakers had "turned back the clock" and "ignored advances in scientific research and evolving standards of humanity and decency."
To support their constitutional claims, the plaintiffs summoned expert witnesses who testified about the effects on the human body of electrocution and being shot by bullets.
Dr. Jonathan Arden, a forensic pathologist, testified that gunshot wounds to the chest cause extensive damage, including fractures of the ribs and sternum. Arden said that when the heart ceases delivering blood to the brain after being shot, a person would remain sensate — or able to perceive through the senses — for at least 15 seconds, during which they might experience excruciating pain. But if the heart is not completely disabled, the sensation and the pain could last longer.
Arden also testified about severe injuries caused by electrocution, describing the effects of electrical and thermal burns on tissue and organs as "the equivalent of cooking." Arden said that if a person were still conscious during the electrocution, they would experience "horrific pain" because of the burns, according to an account of the testimony contained in Judge Newman's order.
Testifying for the state, Dr. Ronald Wright, a forensic pathologist, said that when a person is electrocuted with very high-voltage current, they are immediately rendered unconscious and cannot regain consciousness because their brain cells have been damaged. Even if that doesn't happen, Wright said, a person will die quickly because the human heart violently contracts right after the current is discharged.
"If I had been sentenced to die, that would be my choice because it doesn't hurt," Wright said during the testimony, though he was unable to explain electrocutions during which people being executed breathed, moved and screamed after the application of electric current, according to the order.
Judge Newman ultimately found that the effect of the firing squad "constitutes torture" and that the method is cruel, unusual and corporal — in this context meaning that it mutilates the human body — and thus in violation of the state constitution.
The judge reached a similar conclusion about the electric chair, saying that because the human skull is significantly more resistant to electrical current than other parts of the body, not all of the current applied in the first two rounds will enter a person's brain, increasing the likelihood that they would still be conscious during the last application of current, which causes more pain.
"This creates a risk that an inmate will remain conscious and sensate while he is burned, bruised, and suffocated," Judge Newman wrote.
But in July 2024, the state Supreme Court overturned that decision. The court found that the 2021 statute "as a whole is constitutional" because it guarantees every person facing execution at least one constitutional method, and allows the individual, not the state, to choose among them. The court held that the availability of multiple options means no one could ever be executed by a method they consider more painful than another available alternative.
"If any condemned inmate in this State believes that any one of the three methods of execution now set forth in section 24-3-530 is unconstitutional, he has two other constitutional choices," the court said.
Sigmon was executed by a firing squad on March 7. Owens and Moore were put to death last year by lethal injection.
How Each Execution Method Kills a Person
| Method | The Way It Works | What Causes Death |
|---|---|---|
| Lethal injection | A person is strapped to a gurney and heart monitors are placed on the skin. Intravenous lines are inserted into a vein, typically in the arms. Depending on the state protocol, either a single drug or three different ones are pumped into the bloodstream. | The anesthetic overdose causes respiratory and cardiac arrest in the unconscious person. |
| Electrocution | A person is restrained to a wooden chair, and copper electrodes are attached to a leg and to the head using a headpiece. A sponge soaked in a conductive solution is placed between the scalp and the head electrode. A 2,000-volt electric current is applied for 4.5 seconds, followed by a 1,000-volt current for eight seconds, ending with 120 volts of electric current for two minutes. | The rounds of high-voltage current disrupt bodily functions such as respiration and circulation, causing electrical burns and ultimately resulting in death. |
| Firing squad | A person is strapped into a chair. A physician places an aiming point over the heart and covers the person's head with a hood. When directed, members of a firing team aim their rifles at the person's chest and fire. Vital signs are checked periodically until none are present, at which time the physician certifies death. Additional volleys are authorized if vital signs persist after the first shots. | Destruction of the heart, which stops the circulation of oxygenated blood to the brain. |
| Nitrogen hypoxia | A person is strapped to a gurney and fitted with a respirator designed for industrial use. Pure nitrogen is flowed into the mask, depriving the brain and body of oxygen. | Asphyxiation resulting from the body and brain being deprived of oxygen. |
Over the last two decades, litigating how states kill has become less about proving a method is cruel and more about clearing an ever-rising legal bar.
Ruling in Baze v. Rees in 2008, the U.S. Supreme Court built a framework, later sharpened in 2015's Glossip v. Gross, and 2019's Bucklew v. Precythe, that requires petitioners to clear two high hurdles.
In Baze, the court made clear that executions can involve pain, and that only a "substantial risk of severe pain" as compared to the available alternative execution methods violates the Eighth Amendment.
In Glossip, the court said that to prevail in a method of execution challenge, a petitioner must also identify an alternative method that is "feasible, readily implemented" and would significantly reduce the risk of severe pain.
And in Bucklew, the Supreme Court required federal courts to focus on the prisoner's risk of severe pain and expanded the state's ability to reject alternatives, setting an even higher bar for people challenging executions. That ruling directed courts to distinguish between physical pain, which matters in a constitutional claim, and psychological terror or fear, which generally does not.
States, on the other hand, can reject alternative methods for reasons such as logistics, availability and security. Also, states are not required to adopt untried and untested execution methods.
Robin Maher, executive director of the Death Penalty Information Center, said the legal standard set by the Supreme Court has effectively shut down meaningful review of execution methods under the Eighth Amendment.
"Where we used to be in a conversation about what is cruel and unusual under the amendment, we are now looking at a standard that is so very high and out of reach that those claims are largely futile," she said. "We never even get to the question, because no one can meet the standard to even bring the claim and the United States Supreme Court has said it will not look at those cases."
Some legal scholars say the court's approach also ignores the basic power imbalance between people facing execution and the states seeking to kill them.
Meghan Ryan, a professor at Southern Methodist University's Dedman School of Law, said that by placing the burden on petitioners, the court is stacking the deck against challenges to methods of execution, which require the work of skillful attorneys and expert testimony.
"It's, I think, difficult to put that onus on someone who's stuck in prison to try to figure this out and have the expertise, whereas the government has all the resources at its disposal," Ryan said.
Despite botched executions involving lethal injection, firing squad and nitrogen hypoxia across several states during the last decade, the Supreme Court has refused to step in.
"They've said, very clearly, 'It's not our business to be interfering in what the states choose to do,'" Maher said.
As a result, more lawyers have begun shifting their efforts toward state constitutions, which sometimes offer broader protections — though, as South Carolina's high court showed, state courts are not necessarily more receptive.
Challenging an Untested Method
In June 2018, after Alabama lawmakers authorized nitrogen hypoxia as a method of execution, the state gave people on death row 30 days to decide whether to opt into the new, untested method, or remain with lethal injection, the state's standard practice. At the time, the state had not yet established a protocol for nitrogen hypoxia executions.
Boyd, who was convicted for his role in the 1993 kidnapping and murder of Gregory Huguley and sentenced to death after a jury recommended capital punishment in a 10-2 vote, was among those who chose nitrogen.
A string of botched lethal injections across the country in the years leading up to that moment weighed heavily on Boyd. This included the failed February 2018 execution of Doyle Lee Hamm in Alabama, in which Hamm was strapped to a gurney for 2½ hours as a team repeatedly tried and failed to find a vein. Those cases convinced Boyd that nitrogen gas, which officials claimed causes a person to lose consciousness and die "within minutes," was the option most likely to spare him the greatest amount of suffering.
But after Alabama began to perform executions with nitrogen gas in January 2024, when the state executed Kenneth Eugene Smith, Boyd changed his mind.
Witnesses to Smith's execution saw him convulse and struggle against his restraints for several minutes after the gas began flowing into his mask. Some described him as shaking violently, gasping for air and clenching his fists.
"We didn't see somebody go unconscious in 30 seconds. What we saw was minutes of someone struggling for his life," Jeff Hood, Smith's spiritual adviser who was in the execution chamber with him, told reporters afterward. "We saw minutes of someone heaving back and forth. We saw spit. We saw all sorts of stuff develop from his mask."
On July 16, Boyd filed a suit asking a federal court to prevent the state from using nitrogen hypoxia to kill him. Boyd argued that the method violated the Eighth Amendment because it would cause him to experience extreme pain and terror from being deprived of oxygen, which he described as "conscious suffocation."
By the time he lodged his challenge, five more people had been executed with nitrogen gas: four in Alabama and one, Jessie Hoffman Jr., in Louisiana, the first time that state had used the method.
All those executions were marked by signs of struggle by the person being executed, who either shook while restrained on the gurney, clenched their hands, pulled their arms against their restraints and, in some cases, displayed signs of anxiety and fear including rapid eye movement and pupil dilation, Boyd said in his complaint.
Boyd proposed three alternative methods: a firing squad, hanging — which he later dropped as an option — and medical aid in dying, consisting of a potent mix of sedative and paralytic drugs that some states use in medically assisted deaths.
But on Oct. 9, two weeks before Boyd's scheduled execution, U.S. District Judge Emily M. Marks of the Middle District of Alabama denied his motion for a preliminary injunction.
The judge held that Boyd's claims weren't likely to succeed on the merits, writing in her opinion that he had failed the legal tests established by the Supreme Court in Bucklew, Baze and Glossip. Judge Marks also said Boyd waited too long to bring the lawsuit, which he filed nearly two years after Alabama released its nitrogen protocol in August 2023.
In her opinion, Judge Marks referred to the Supreme Court rulings, saying the Eighth Amendment does not require a painless death and that psychological distress is inherent in all executions.
A three-judge panel of the Eleventh Circuit upheld the ruling, finding that the district court had correctly applied the Supreme Court precedent.
How Long and How Painful?
In challenges to execution methods, two questions dominate: How long will death take, and will the person be able to feel what is happening to them during that time?
Cornell's Blume said that constitutionally, the amount of time required to kill a person is less important than whether they are insensate, meaning they can't feel anything, including pain.
"It's not just the amount of time," he said. "The issue is the time, and is the person conscious or not?"
Blume noted that even in firing squad executions, which some states claim are swift, the initial shots do not render a person unconscious. The state's assumption is that the heart will be obliterated instantly, cutting off blood supply to the brain so rapidly that consciousness fades within seconds. But when shots miss or fail to destroy the heart, he said, the person could be conscious for significantly longer.
"It's going to hurt like hell, and it's going to shatter their rib cages," he said. "But the question is: How long before all the blood bleeds out?"
The April 11 firing squad execution of Mikal Deen Mahdi in South Carolina provides a case in point. An autopsy report showed that Mahdi had only two gunshot wounds to his chest, indicating that one of the three riflemen tasked with the execution missed the target completely. But the report also showed that the shooters who hit him missed his heart, causing a slower death than anticipated.
"He clearly was alive for significantly longer," Blume said.
South Carolina's firing squad protocol has been criticized by experts in other litigation for relying on too few shooters. Utah, another state that uses firing squads, uses five shooters.
Mahdi's execution, the experts said, underscored precisely why Judge Newman had originally found the method "corporal" and "torture" before the state Supreme Court reversed her. No other person sentenced to death in South Carolina has chosen the firing squad since Mahdi's execution.
Pain and timing also played a significant role in the litigation brought in Alabama federal court by Boyd.
Judge Marks' ruling dismissing the suit turned largely on two related questions: How long would Boyd remain conscious under Alabama's nitrogen hypoxia protocol, and what type of suffering, physical or psychological, would he experience during that window?
The court's analysis focused on how long a person remains conscious after oxygen is withdrawn, and whether the deprivation is long enough — and distressing enough — to violate the Eighth Amendment.
Expert witnesses in Boyd's case disagreed on how long that consciousness period would last. Dr. Joseph Antognini, an anesthesiologist testifying for the state, said unconsciousness would come in 35 to 40 seconds, possibly sooner. But Dr. Philip E. Bickler, who testified as Boyd's expert, said it would take about two minutes for a person breathing normally to fall unconscious, a time that could be even longer if they breath shallowly or hold their breath.
Judge Marks found that even taking the facts in the light most favorable to Boyd, he could not meet the legal standard. The court acknowledged that a "primal" drive to breathe would trigger a "terror response" because a person being executed does not want to die, but concluded that it "is true for virtually all executions and does not implicate the Eighth Amendment."
Scientific Study Falls Short
Experts say the scientific study of execution methods is thin and courts struggle to grasp important nuances within it, a gap that scholars say undermines the entire legal framework governing the Eighth Amendment.
Courts are asked to weigh the "substantial risk" of pain associated with a given execution method, yet no meaningful body of science needed to make such judgments exist.
Deborah W. Denno, a professor at Fordham University School of Law who has studied execution protocols for more than three decades and whose writings have been cited by the Supreme Court, said the core problem is that the United States has never developed a real scientific foundation for its methods of execution.
"We just don't know very much on how to kill people," she said. "In this kind of context — executing people as a punishment — it's much more difficult than people realize."
Executions, she explained, aren't designed with scientific rigor because modern medicine focuses on preserving life, not ending it, and because ethical rules preclude the kind of testing that would normally precede the use of techniques that affect a human body so drastically.
Historically, execution methods like electrocution were tested on animals — dogs or even elephants — but that approach is legally and ethically impossible today.
Denno noted that the newest execution method, nitrogen hypoxia, was introduced without even that rudimentary level of evaluation, as "an act of desperation." States turned to it not because of evidence suggesting it was humane, but because lethal injection drugs became difficult to acquire, she said.
"Nitrogen hypoxia has probably been the least examined method of execution," she said.
The scientific vacuum extends to pain, the central concept in modern execution litigation. Neuroscience offers little clarity about what pain looks like in a dying brain or how to measure it.
Ryan, the SMU professor, said that in medicine, patients self-report pain because clinicians have no objective way to quantify it. Courts, she said, face the same limitation, and so judges typically end up relying on witness descriptions of botched executions — things like body movements, gasping and vomiting — rather than on scientifically validated indicators of suffering.
"We don't know a whole lot about pain," she said. "We don't even have any means by which to measure it."
Yet the Supreme Court's modern doctrine demands a precise accounting of pain as part of the framework established under Baze, Glossip and Bucklew. Those cases moved away from the prior "evolving standards of decency" test that made room for new scientific knowledge.
Ryan noted that as the court turned more conservative starting in President Donald Trump's first term with the addition of Justices Brett Kavanaugh, Neil Gorsuch and Amy Coney Barrett, it has increasingly embraced an originalist framework that looks to 18th-century practices surrounding the application of the death penalty, even though those practices say little about modern physiology or the neuroscience of suffering.
Meaningfully incorporating science to try to answer the question of which execution methods can pass constitutional muster, Ryan said, would require robust factual development at the trial level: expert testimony, autopsies, toxicology reports and detailed analysis of how different mechanisms cause distress.
But that rarely happens, she said; capital defendants usually lack the resources to build such a record, and prosecutors have no incentive to deepen the scientific inquiry. Trials often proceed with a narrow evidentiary base that leaves judges to resolve questions science itself cannot answer, she said.
Even collecting data during executions — for example, monitoring vital signs, measuring brain activity or recording physiological responses — is practically difficult, Ryan said. States restrict who may witness executions and enact secrecy laws to shield protocols, drug sources and staff identities.
"I don't know that they want to do further research on these types of issues," Ryan said. "I would imagine that information would not be good for the government."
A State That Obscures Its Methods
While some states push forward with new execution methods, others are fighting to keep old ones hidden from view.
In Tennessee, a sweeping lawsuit is targeting the secrecy of the state's lethal injection protocol, a challenge that strikes at what one attorney calls a "culture of recklessness and non-compliance" within the state's Department of Correction.
Kelley Henry, a supervising attorney with the Federal Public Defender's Office in Nashville, is leading the suit on behalf of seven men on death row. The case, filed in Tennessee's Chancery Court, is set for trial in April and raises Eighth Amendment and First Amendment claims.
At its core is an allegation that the state has been using execution drugs procured through the so-called gray market, in which medications start in the legitimate medical supply chain but are later diverted and sold without oversight from the U.S. Drug Enforcement Administration. The lawsuit also alleges that officials have repeatedly misled courts and the public about drug testing and potency as well as their failures to comply with their own protocol.
Henry said the challenge grew out of discoveries made three years ago, when lawyers learned the state's Department of Correction had given false testimony about the drugs used in prior executions. According to Henry, the old protocol required the state to test the compounded chemicals before use — tests that, in many cases, never happened. In other cases where testing was performed, the drugs were found not potent enough to be reliable in executions.
"We are trying to get as much information as we can about the drugs that are being used," she said, "because if they are adulterated, cut, poorly stored, poorly handled, not kept at the appropriate temperature during transport, then that poses a problem and a risk for our clients."
She pointed to the 2018 execution by lethal injection of Billy Ray Irick, where witnesses reported visible signs of suffering, and to the case of her former client Byron Black, who during his Aug. 5 lethal injection continued to exhibit movement well past the point when the state's expert said he should have been unconscious.
"Something went wrong in his execution," Henry said. "We're investigating why that happened."
The underlying problem, Henry said, is secrecy. Tennessee's Public Records Act shields the identities of execution participants, and state courts have repeatedly barred defense teams from obtaining information about the individuals and companies involved in sourcing, storing and compounding the drugs used for lethal injections.
Henry said that lack of transparency has allowed violations to go unchecked.
"What we're finding is that lack of accountability is leading to the department's being reckless in the executions, because at the end of the day, the person is dead, and that was the goal, and that's all they care about," she said.
Henry said Tennessee spent $600,000 on execution drugs, creating powerful incentives for illicit suppliers.
"There's a huge market incentive to cut the drugs with something else," she said. "The trend that I'm seeing is the state doubling down on lack of transparency."
--Editing by Orlando Lorenzo and Alanna Weissman.
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