Lethal injection is a method of execution that puts a condemned person to death by delivering one or more drugs through an intravenous line. It is the primary execution method in the United States, authorized in most of the 27 states that still carry out capital punishment, as well as by the federal government and the U.S. military. The drugs are given either as a single large dose of a barbiturate or as a three-drug sequence that first renders the person unconscious, then paralyzes the muscles, then stops the heart.
Why This Method Exists
Oklahoma became the first state to adopt lethal injection in 1977, after a state legislator asked the state medical examiner, A. Jay Chapman, to design a more humane execution method. Chapman drafted a three-drug protocol in a single day. His sequence became the national template: an anesthetic to produce unconsciousness, a paralytic to stop breathing, and potassium chloride to stop the heart. Texas carried out the first lethal injection execution in 1982, and within a decade most death-penalty states had moved away from electrocution, gas, hanging, and firing squads in favor of what looked like a cleaner, more clinical alternative.
The Drugs Used
The original three-drug protocol relied on sodium thiopental, a fast-acting barbiturate, to induce deep unconsciousness. The second drug, pancuronium bromide, paralyzed the muscles and halted breathing. The third, potassium chloride, triggered cardiac arrest. That combination held for roughly thirty years.1Federal Register. Request for Information Regarding the Use of Pentobarbital in Federal Executions
When sodium thiopental became unavailable in the early 2010s, states switched to pentobarbital, another barbiturate. Several moved to a single-drug protocol, administering a lethal dose of pentobarbital alone to cause unconsciousness followed by respiratory and cardiac failure. The federal government adopted this single-drug pentobarbital protocol in 2019.1Federal Register. Request for Information Regarding the Use of Pentobarbital in Federal Executions
Other states substituted midazolam, a sedative from the benzodiazepine family, for the barbiturate in a modified three-drug protocol. Midazolam was not designed to produce the deep surgical anesthesia needed to prevent pain from the paralytic and potassium chloride, and its use became the center of intense litigation after several prolonged executions raised questions about whether inmates remained conscious during the process.2PMC. The Role of Anaesthesiologists in Lethal Injection: A Call to Action
How the Procedure Works
Protocols vary by jurisdiction, but the physical sequence is consistent. The condemned person is strapped to a padded gurney with restraints on the arms, legs, and torso. An execution team inserts two intravenous lines: a primary line and a backup, in case one fails. Establishing IV access is one of the most failure-prone steps, particularly with inmates whose veins have deteriorated with age, illness, or prior drug use.
Once the lines are in place, the drugs are delivered in sequence, either manually by the execution team or through a mechanized system operated from an adjacent room. In a three-drug protocol, the anesthetic goes first, followed by the paralytic and then the potassium chloride. In a single-drug protocol, the barbiturate alone is pushed through the IV at a dose far exceeding anything used in medicine. A physician or other official monitors cardiac activity and pronounces death after the heart stops. The specific monitoring role varies by state because of ethical restrictions on physician participation.
Before the drugs are administered, most states offer the condemned a final meal and the chance to make a final statement. Neither is constitutionally required, and the rules differ widely. Executions are not private. State law and prison policy determine who watches from viewing rooms separated from the chamber by glass, including family members of the victim, family members of the condemned, law enforcement officials, prosecutors, and members of the media.
When Executions Go Wrong
Lethal injection was designed to look clinical, but the reality has not always matched. Researchers have estimated that more than 7 percent of lethal injections through 2009 involved significant complications, making it the most frequently botched execution method. The rate has worsened as states have turned to unfamiliar drug combinations and less reliable suppliers. In 2022, complications occurred in roughly a third of execution attempts nationwide.
The most common point of failure is IV access. Execution team members are not usually physicians or nurses, and finding a viable vein in someone who has spent decades in prison can be genuinely difficult. In one Idaho case in 2024, the team attempted to establish a line eight times before the inmate’s veins collapsed and the execution was called off.
Drug-related failures run deeper. An analysis of autopsies from more than 200 lethal injection executions found that 84 percent showed evidence of pulmonary edema, a fluid buildup in the lungs that experts compare to the sensation of drowning. Because the paralytic prevents visible movement, witnesses may see what looks like a peaceful death while the inmate experiences something far worse. The three-drug protocol was designed in part to spare witnesses from distress; critics argue the paralytic may simply mask suffering rather than prevent it.
Why Doctors Don’t Participate
Lethal injection borrows the tools of medicine, but the medical profession has refused to lend its expertise. The American Medical Association’s Code of Ethics prohibits physicians from participating in executions. The ban covers administering the drugs, selecting injection sites, starting IV lines, monitoring vital signs, prescribing or preparing the drugs, and even providing technical advice to the execution team.3American Medical Association. Capital Punishment
The American Nurses Association has held a parallel position since 1983, stating that participation in executions, whether by inserting a catheter, injecting the drugs, or monitoring the procedure, is incompatible with the ethical foundations of nursing.4American Nurses Association. Capital Punishment and Nurses’ Participation in Capital Punishment
The result is a procedure modeled on medical practice that cannot legally or ethically be performed by medical professionals. Execution teams are staffed instead by corrections personnel whose training varies, and that gap is a recurring factor in botched executions.
Drug Shortages and Secrecy
The pharmaceutical industry’s retreat from the execution business has reshaped lethal injection more than any court ruling. In 2011, Hospira, the only U.S. manufacturer of sodium thiopental, permanently ceased production. The company had explored moving manufacturing to Italy but abandoned the plan after the Italian government insisted on guarantees that the drug would not be used in executions.
The European Union later imposed export controls on drugs that could be used for capital punishment, cutting off what had been an alternative supply line for American corrections departments.5Legislation.gov.uk. Regulation (EU) 2019/125 of the European Parliament and of the Council Concerning Trade in Certain Goods Which Could Be Used for Capital Punishment, Torture or Other Cruel, Inhuman or Degrading Treatment or Punishment (Codification)
The scarcity pushed states into improvisation. Some adopted single-drug pentobarbital. Others experimented with midazolam-based combinations. A number turned to compounding pharmacies, which mix drugs to order rather than manufacturing at scale, raising concerns about potency and sterility. Several states enacted secrecy laws to shield the identity of their drug suppliers, making independent verification of drug quality nearly impossible.
What the Constitution Allows
The Eighth Amendment’s ban on cruel and unusual punishment is the legal lens through which courts evaluate lethal injection. Three Supreme Court decisions shape the framework.
In Baze v. Rees (2008), the Court upheld Kentucky’s three-drug protocol and set the governing standard: an execution method violates the Eighth Amendment only if it presents a “substantial” or “objectively intolerable” risk of serious harm. A state’s refusal to adopt a proposed alternative method is unconstitutional only if the alternative is feasible, readily implemented, and would significantly reduce a substantial risk of severe pain.6Law.Cornell.Edu. Baze v. Rees
In Glossip v. Gross (2015), the Court upheld Oklahoma’s use of midazolam, accepting the lower court’s finding that a 500-milligram dose would render an inmate sufficiently unconscious even though midazolam is not approved as a sole surgical anesthetic. The Court emphasized that the inmates had failed to identify a known and available alternative, a requirement that has become the central hurdle in these challenges.7Justia U.S. Supreme Court Center. Glossip v. Gross
In Bucklew v. Precythe (2019), the Court applied the same framework to inmates with unique medical conditions. Russell Bucklew suffered from a rare vascular condition and argued lethal injection would be exceptionally painful for him; he proposed nitrogen gas as an alternative. The Court rejected the claim, holding that the alternative-method requirement applies whether the challenge targets a protocol generally or as applied to a particular person, and that Bucklew had not shown nitrogen hypoxia was readily implemented at the time.8Supreme Court of the United States. Bucklew v. Precythe
The practical effect is that inmates bear a heavy burden. They must prove the state’s method creates a substantial risk of serious harm and identify a specific, workable alternative that would reduce that risk. Without both, the challenge fails.
Where Lethal Injection Stands Now
As of 2025, 27 states authorize capital punishment, and most designate lethal injection as the primary method.9Federal Register. Manner of Federal Executions That dominance is beginning to crack. Idaho enacted legislation making the firing squad its primary method effective July 2026, with lethal injection as backup, after the failed IV attempt that halted an execution there. Several states keep electrocution or firing squad on the books as alternatives when lethal injection drugs are unavailable or protocols face court challenges.
The federal government resumed executions under a single-drug pentobarbital protocol in 2020 after a 17-year pause, carrying out 13 federal executions in the final months of the Trump administration. A moratorium followed in 2021 under the Biden administration. In January 2025, an executive order declared it the policy of the United States to “ensure that the laws that authorize capital punishment are respected and faithfully implemented,” signaling a return to federal executions.10The White House. Restoring the Death Penalty and Protecting Public Safety
The most significant alternative method to emerge is nitrogen hypoxia, which kills by replacing breathable air with pure nitrogen and causing oxygen deprivation. Alabama carried out the first nitrogen gas execution in the world in January 2024. Four states, Alabama, Louisiana, Mississippi, and Oklahoma, have authorized the method, and Louisiana carried out its own nitrogen execution in 2025. The shift was driven in part by the same drug-supply problems that have reshaped lethal injection, though Alabama’s first use drew criticism after witnesses reported that the inmate convulsed and appeared to struggle for several minutes before dying.