Oklahoma’s Invention of Nitrogen Hypoxia Executions

The “Fool-Proof” Execution Method : How Oklahoma’s Invention of Nitrogen Hypoxia Executions Repeated an Old Mistake

On April 29, 2014, the execution of Clayton Lockett in Oklahoma took forty agonizing minutes. Lockett writhed, groaned and attempted to lift himself from the gurney as the lethal injection drugs failed to work as intended. The scene, witnessed by journalists and officials alike, became national news…and set off a chain of events that would lead Oklahoma to pioneer a new method of execution that, its proponents promised, was utterly “fool-proof.”

That promise, and what became of it, is the subject of my latest book Suffocation by Design…a rigorous examination of how nitrogen hypoxia was adopted, what the science actually showed and what happened when theory met reality in the execution chamber (which I have witnessed twice).

Oklahoma’s Invention of Nitrogen Hypoxia Executions: A Crisis in Search of a Solution

The political pressure following the Lockett execution was enormous. Supporters of capital punishment feared that continued failures would invite judicial intervention or fuel calls for abolition. Opponents pointed to Lockett as proof that the death penalty was irredeemably flawed. In this atmosphere, Oklahoma legislators felt an urgent obligation to demonstrate that the state could execute people without visible chaos.

Their answer was nitrogen hypoxia: a method by which an inert gas would replace oxygen in the condemned person’s lungs, inducing unconsciousness and death without the complications that had made lethal injection so problematic. Representative Mike Christian, one of the method’s chief advocates, described it as practical, efficient, humane and innovative…and repeatedly called it “fool-proof.” Senator Ervin Yen, a cardiac anesthesiologist, lent medical credibility to the proposal, assuring lawmakers that nitrogen hypoxia avoided the carbon dioxide buildup that triggers the panic response associated with suffocation.

The logic appeared scientifically sound on its surface. Because nitrogen is inert and does not cause CO₂ accumulation, proponents argued, the condemned person would simply lose consciousness peacefully…almost as if falling asleep. Unlike lethal injection, nitrogen hypoxia required no difficult to obtain drugs, no trained medical personnel to establish IV lines and no complex drug protocol. Place a mask over the condemned person’s face, turn on the gas and wait. What could go wrong?

Oklahoma’s Invention of Nitrogen Hypoxia Executions: A Legislature in Haste

What is striking about Oklahoma’s legislative process is not just the confidence with which the method was endorsed, but the speed and insularity with which it was adopted. The bill passed the House by a vote of 85 to 10 and cleared the Senate unanimously, 41 to 0. Governor Mary Fallin signed it into law on April 17, 2015…less than a year after the Lockett execution. From introduction to passage, the process took only weeks.

There were no extended committee hearings featuring independent expert witnesses. There was no pilot program, no feasibility study, no consultation with other states. Industrial gas suppliers…whose cooperation would be essential to any implementation…were not consulted. Independent anesthesiologists, medical ethicists and specialists in human physiology were notably absent from the proceedings. The debate was conducted largely among Oklahoma lawmakers and a small circle of supporters.

Legal scholar Deborah W. Denno, a prominent expert on execution methods, described nitrogen hypoxia as “experimental” and highlighted three critical problems: the complete absence of human trials, a vague protocol that left crucial procedural details undefined and the impossibility of confirming whether the method actually produced the effects its proponents claimed. A legislative researcher who supported the bill cited analogies to pilots experiencing oxygen deprivation at altitude and victims of accidental nitrogen exposure…circumstances that differ substantially from a conscious, restrained person anticipating their death.

These warnings were not adequately examined. The few legislators who expressed reservations were marginalized. The political calculus was straightforward: doing nothing was not an option and nitrogen hypoxia offered a path forward that could command overwhelming support.

The Pattern of Execution History

Oklahoma’s experience did not occur in isolation. It is the latest iteration of a pattern that has defined American execution practice for over a century. Each method…hanging, the electric chair, the gas chamber, lethal injection…was introduced with confidence that science and expertise had finally produced a reliable, humane solution. Each eventually revealed unexpected complications that its proponents had not anticipated.

The electric chair, adopted in the late nineteenth century as a more humane alternative to hanging, frequently caused burning, convulsions and prolonged suffering. Witnesses described smoke rising from bodies and condemned prisoners who remained conscious through multiple jolts of electricity. The gas chamber, promoted as an improvement, produced its own horrors…inmates gasping and struggling as carbon dioxide accumulated, with the process sometimes taking many minutes. Lethal injection, invented in the 1970s to resemble a clinical medical procedure, accumulated problems over decades: drug shortages, questions about whether paralytic agents masked suffering and a series of botched executions culminating in Lockett.

The recurring gap between theoretical promise and operational reality is not incidental…it reflects something fundamental about the enterprise. Each generation of lawmakers convinces itself that this time, the science is solid enough, the method simple enough, the safeguards sufficient. And each time, the physiological complexity of human death resists easy management.

When Oklahoma’s Theory Met Reality

The assumptions underlying nitrogen hypoxia collided with empirical reality on January 25, 2024, when Kenneth Eugene Smith became the first person in the United States executed using the method, in Alabama. State officials had assured both the public and the courts that unconsciousness would occur within seconds, followed quickly by a painless death. Witnesses would see nothing disturbing.

What witnesses actually saw was something different. Smith remained conscious for several minutes, his body convulsing as he gasped and retched. The autopsy revealed pulmonary edema…fluid accumulated in the lungs…directly contradicting the assurances that nitrogen hypoxia would be physiologically clean and uncomplicated. Subsequent executions in Alabama and Louisiana produced the same pattern: extended consciousness, violent physical reactions and observable distress lasting far longer than officials had promised.

These were not isolated implementation errors. They were consistent across multiple executions, suggesting systematic problems with the method’s underlying assumptions. The physiological reality is that the human body responds to sudden oxygen deprivation in ways that are not fully predictable: blood pressure can spike, muscle control can be lost, the cardiovascular system may struggle to compensate and the subjective experience of the condemned person…what they actually perceive in those minutes…cannot be known.

The Greatest Irony of Oklahoma’s Invention of Nitrogen Hypoxia Executions

Perhaps the sharpest irony in Oklahoma’s story is this: after pioneering the legislation, the state watched as Alabama and Louisiana became the testing grounds for the method it had championed. In January 2024, Governor Kevin Stitt announced that Oklahoma had no plans to use nitrogen hypoxia. The state that had passed the bill with near-unanimous votes, that had called the method “fool-proof,” quietly stepped back as other states bore out exactly the complications that skeptics had warned about. Oklahoma had legislated in haste and had the rare opportunity to observe the consequences from a distance…consequences that confirmed what a more deliberate process might have prevented.

United Nations human rights experts have described nitrogen gas executions as constituting cruel, inhuman and degrading treatment under international law. Legal challenges have followed, raising questions about whether states can implement the method in a manner consistent with the Eighth Amendment’s prohibition on cruel and unusual punishment.

Oklahoma’s Invention of Nitrogen Hypoxia Executions: The Institutional Lesson

Oklahoma’s experience offers a clear lesson in the dangers of policymaking under conditions of urgency and political pressure. When lawmakers convinced themselves that the science was simple and the solution straightforward, they bypassed the careful analysis that any significant policy innovation requires…especially one involving matters of life and death. They gave disproportionate weight to confident assertions from supporters, dismissed skeptical voices and allowed the pressure to act quickly to overwhelm deliberative process.

The institutional lesson, as Suffocation by Design makes clear, is precisely this: crisis conditions and political urgency are the circumstances under which careful deliberation is most important, not least important. The obligation to proceed thoughtfully is greatest when the stakes are highest.

Nitrogen hypoxia is the latest chapter in a long history of searching for a “fool-proof” method of execution. The evidence now accumulating suggests, as similar evidence has always eventually suggested, that human physiology and death itself resist easy control…and that promises of simplicity should be met with the scrutiny that Oklahoma’s legislature failed to provide.

Suffocation by Design is available for purchase here.

Sign the petition to oppose nitrogen executions here.