Lethal injection is a method of execution in which drugs are injected into the bloodstream to cause death, used as the primary execution method in nearly every U.S. death-penalty state as well as by the federal government and the military.1National Conference of State Legislatures. States and Capital Punishment It was designed to look clinical and painless. Decades of use have revealed something more complicated: drug shortages that have forced states to switch protocols repeatedly, secrecy laws that hide where the drugs come from, prolonged and visibly troubled executions, and a line of Supreme Court decisions that make the procedure extremely hard to challenge in court.
How the Procedure Works
The condemned person is escorted to the execution chamber and strapped to a gurney. An intravenous team inserts two IV catheters, one primary and one backup, preferably in the arms. The IV lines run through a wall or partition to an adjacent room where the execution team pushes the drugs out of direct view of witnesses.2Kentucky Legislative Research Commission. 501 KAR 16:330 Lethal Injection Protocols
In a three-drug protocol, the anesthetic goes in first, followed by a saline flush, then the paralytic, another flush, and finally potassium chloride. In a single-drug protocol, the team injects a large dose of pentobarbital. After the final injection, the team watches a heart monitor and waits for a flat line, and a coroner then enters the chamber to declare death. If the heart has not stopped within 20 minutes of the final injection, the backup IV may be used to administer a second round of drugs.2Kentucky Legislative Research Commission. 501 KAR 16:330 Lethal Injection Protocols
Who actually pushes the drugs matters. The American Medical Association’s Code of Ethics prohibits physicians from participating in executions in any capacity, including selecting injection sites, starting IV lines, prescribing or preparing the drugs, monitoring vital signs, or even observing in a professional role.3American Medical Association. Capital Punishment A method designed to mimic medical practice is carried out by people the medical profession refuses to send. States staff execution teams with paramedics, emergency medical technicians, phlebotomists, and military corpsmen, and most keep their identities anonymous.
The Drugs
The Original Three-Drug Sequence
From the 1980s through the early 2010s, almost every state used the same three drugs in the same order. Sodium thiopental, a fast-acting barbiturate, was supposed to render the person deeply unconscious within seconds. Pancuronium bromide, a paralytic, then stopped all voluntary muscle movement, including breathing. Potassium chloride disrupted the heart’s electrical signals and caused cardiac arrest.4PMC. Lethal Injection for Execution: Chemical Asphyxiation?
The sequence depends on the first drug working. If the anesthetic fails to produce deep unconsciousness, the person feels the paralytic lock their muscles while they suffocate, then the searing pain of potassium chloride stopping the heart. The paralytic also masks any outward sign of distress, so witnesses cannot tell whether the person is conscious. That design flaw sits at the center of most medical and legal objections to the three-drug approach.
The Shift to Pentobarbital, Then Midazolam
In 2011, Hospira, the sole American manufacturer of sodium thiopental, permanently stopped making it. The company said it could not prevent diversion of the drug to corrections departments, which conflicted with the position of Italian authorities where it was manufactured.5Hospira Inc. Statement From Hospira That same year, the European Union imposed export controls on barbiturate anesthetics to block their use in executions.6European Commission. Commission Extends Control Over Goods Which Could Be Used for Capital Punishment or Torture
Many states switched to pentobarbital, another barbiturate, used alone in a single-drug protocol. A large dose causes unconsciousness, respiratory failure, and cardiac arrest without the need for a paralytic or a separate heart-stopping agent.7Death Penalty Information Center. State-by-State Execution Protocols Then pentobarbital supplies also dried up as its Danish manufacturer, Lundbeck, moved to block sales for executions.
Several states turned to midazolam. It is a benzodiazepine, not a barbiturate, and it works as a sedative rather than a true anesthetic. Critics have long argued it cannot reliably produce the deep unconsciousness needed to prevent suffering, and the drug’s own inventor opposed its use for executions. Midazolam was involved in a string of visibly troubled executions, including those of Dennis McGuire in Ohio, Clayton Lockett in Oklahoma, Joseph Wood in Arizona, and Ronald Smith in Alabama. In 2017, a federal magistrate judge barred Ohio from using midazolam, finding it created a “substantial and objectively intolerable risk of serious pain and suffering.” Arizona later agreed never to use the drug again.
What the Drugs Do to the Body
Barbiturates like sodium thiopental and pentobarbital suppress the central nervous system and rapidly produce unconsciousness at high doses. Breathing slows and stops, and the brain, starved of oxygen, ceases functioning. In a three-drug protocol, the paralytic independently halts breathing by freezing the diaphragm and intercostal muscles, and potassium chloride overwhelms the heart’s electrical system to trigger cardiac arrest.4PMC. Lethal Injection for Execution: Chemical Asphyxiation?
The clean appearance of the process may obscure something else. An NPR investigation reviewed more than 200 autopsy reports from executions across nine states between 1990 and 2019 and found pulmonary edema, a condition in which fluid fills the lungs, in 84% of cases. Pulmonary edema produces a sensation similar to drowning or suffocation. Because the paralytic prevents outward movement, a person experiencing it would show no visible distress. Whether the anesthetic reliably prevents the person from feeling it remains one of the most contested questions in the field.
Botched Executions
Lethal injection was presented as the most reliable execution method. The record cuts the other way. Research covering executions from 1890 to 2010 found that lethal injection had the highest botched-execution rate of any method at 7.12%, compared with 5.4% for lethal gas, 3.12% for hanging, and 1.92% for electrocution.8Death Penalty Information Center. Botched Executions
The problem has not improved as drug supplies have deteriorated. In July 2022, Alabama’s execution of Joe Nathan James Jr. lasted roughly three and a half hours, with three hours spent trying to establish IV access behind closed doors. A private autopsy later revealed cuts, deep bruising, and puncture wounds across his hands, wrists, elbows, and feet. Two months later, Alabama tried and failed to execute Alan Miller after 90 minutes of unsuccessful attempts to find a usable vein. In November 2022, officials abandoned the execution of Kenneth Smith after more than an hour of failed IV attempts left him hyperventilating and dizzy. Arizona carried out three lethal injection executions in 2022, all of which involved significant complications, including one in which the execution team cut into the prisoner’s groin to access a vein.
The recurring issue shares a root cause. The procedure depends on reliable intravenous access, and the people performing it are not physicians.
Drug Procurement and Secrecy Laws
Cut off from commercial pharmaceutical channels after 2011, states turned to compounding pharmacies, small operations that mix drugs from raw ingredients. Compounded drugs do not require FDA approval and may not meet the same quality standards as mass-produced pharmaceuticals. Missouri was later revealed to have made secret cash payments to a Tulsa compounding pharmacy that allegedly lacked proper licensing, and a federal judge barred that pharmacy from supplying execution drugs to the state.
To protect their supply chains from public pressure and legal challenges, many states have passed laws shielding the identity of execution drug suppliers. Georgia classifies the identity of anyone who manufactures, supplies, or compounds execution drugs as a confidential state secret. Indiana, Missouri, Ohio, Oklahoma, and several other states have similar protections. These statutes make it difficult for courts and the public to evaluate the quality or source of the drugs, and the secrecy itself has become a flashpoint in litigation over whether specific protocols risk unnecessary pain.
Constitutional Challenges Under the Eighth Amendment
The Eighth Amendment prohibits cruel and unusual punishment, and inmates have repeatedly argued that lethal injection crosses that line. Three Supreme Court decisions set the framework.
Baze v. Rees (2008)
The Court upheld Kentucky’s three-drug protocol and held that an execution method violates the Eighth Amendment only if it presents a “substantial” or “objectively intolerable” risk of serious harm. An isolated mishap is not enough. The Court also held that a state’s refusal to adopt an alternative procedure violates the Constitution only if the alternative is feasible, readily implemented, and would significantly reduce a substantial risk of severe pain.9Legal Information Institute. Baze v. Rees
Glossip v. Gross (2015)
The Court raised the bar. A prisoner challenging an execution method must identify a known and available alternative that would entail a lesser risk of pain.10Justia Law. Glossip v. Gross Showing that the state’s protocol risks serious suffering is not enough; the prisoner must also point to a specific, practical alternative. The case involved Oklahoma’s use of midazolam, and the majority concluded the inmates had not shown that midazolam created a substantial risk of harm compared with available alternatives.
Bucklew v. Precythe (2019)
The Court confirmed that the Baze–Glossip test applies to all Eighth Amendment challenges to execution methods, including as-applied challenges brought by individual prisoners with unique medical conditions. A prisoner must show both a feasible and readily implemented alternative method that would significantly reduce a substantial risk of severe pain, and that the state refused to adopt it without a legitimate penological reason.11Supreme Court of the United States. Bucklew v. Precythe
The practical effect is that challenging a lethal injection protocol in court is very difficult. A prisoner cannot simply argue the drugs will cause pain. They must essentially design an alternative execution protocol and prove it is better, a burden few have met.
Where Lethal Injection Stands Today
Capital punishment is currently authorized in 27 states, by the federal government, and by the U.S. military, and lethal injection remains the primary method in nearly all of those jurisdictions.1National Conference of State Legislatures. States and Capital Punishment South Carolina is the exception, having made electrocution its primary method in 2021 with lethal injection and firing squad as secondary options.
At the federal level, a moratorium on executions imposed in July 2021 was lifted by Attorney General memorandum on February 5, 2025, pursuant to an executive order directing the Department of Justice to resume carrying out death sentences.12Office of the Attorney General. Reviving the Federal Death Penalty and Lifting the Moratorium on Federal Executions This followed a period of intense federal activity in 2020 and 2021, when 13 federal executions were carried out in six months after a 17-year hiatus.
Drug shortages and botched-execution litigation have pushed several states toward entirely different methods. Alabama has carried out two executions using nitrogen hypoxia, which involves strapping a respirator mask to the person’s face and piping in pure nitrogen until oxygen deprivation causes death. Louisiana and Mississippi have also authorized nitrogen hypoxia, and Louisiana used the method as recently as 2025.7Death Penalty Information Center. State-by-State Execution Protocols Other states have reauthorized older methods as backups, including electrocution in Tennessee and firing squad in several Western states, each change traceable to the ongoing difficulty of obtaining lethal injection drugs.1National Conference of State Legislatures. States and Capital Punishment
Nearly half a century after lethal injection was introduced, its legitimacy turns on whether the drugs work as intended, whether the people administering them can establish IV access, and whether the secrecy around the drug supply can survive legal scrutiny. Those remain open questions in courtrooms across the country.