Execution methods in the US fall into five categories currently authorized somewhere in the country: lethal injection, electrocution, lethal gas (including nitrogen hypoxia), the firing squad, and hanging. Twenty-seven states, the federal government, and the U.S. military can impose the death penalty, and each jurisdiction picks one primary method and usually one or more backups. Lethal injection is the default nearly everywhere. Which method actually gets used in a given case depends on state law, whether the necessary drugs can be obtained, court rulings, and in some states the condemned person’s own choice.
Lethal Injection
Lethal injection is the primary method in virtually every death-penalty jurisdiction. The condemned person is strapped to a gurney and given two intravenous lines, one primary and one backup. Drugs are administered remotely from an adjacent room. A curtain between the chamber and the witness area is typically opened once the lines are set.
Two protocols are in use. The original three-drug sequence starts with a barbiturate (historically sodium thiopental, later pentobarbital) meant to render the person deeply unconscious, then a paralytic such as pancuronium bromide to stop breathing, then potassium chloride to trigger cardiac arrest. The constitutional dispute over this method for more than a decade has focused on whether the first drug reliably works before the painful second and third drugs take effect.
The single-drug protocol replaces the sequence with one large dose of pentobarbital, causing deep anesthesia, respiratory failure, and death. At least a dozen states and the federal government now authorize or have used this approach. It sidesteps the core concern with three-drug protocols: that an inadequately sedated person would feel the paralytic and potassium chloride but be unable to show it.
Electrocution
Roughly nine states still authorize the electric chair, almost always as a secondary option the condemned person can elect or as a fallback if lethal injection is unavailable. One state currently designates electrocution as its primary method after long-running trouble obtaining injection drugs.
The person is strapped into a chair with electrodes attached to the head and one leg. High-voltage alternating current, typically between roughly 500 and 2,000 volts, is passed through the body in timed cycles. Death results from cardiac arrest and respiratory failure. The method causes severe burns and internal organ damage, and it has drawn more constitutional challenges than most others, though courts have upheld it under existing Eighth Amendment standards.
Lethal Gas and Nitrogen Hypoxia
Two gas-based methods are authorized, and they work through different mechanisms.
Hydrogen Cyanide
A handful of states still authorize the traditional gas chamber. The person is strapped into a chair inside a sealed enclosure, and sodium cyanide pellets are dropped into sulfuric acid beneath the chair to generate hydrogen cyanide gas. The gas blocks cells throughout the body from using oxygen, killing through cellular suffocation rather than airway blockage. The process can take several minutes, and the method has been rarely used in recent decades.
Nitrogen Hypoxia
Nitrogen hypoxia is the newest authorized method. Three states currently allow it, with at least one more having passed enabling legislation in 2025. The person wears a face mask connected to a supply of pure nitrogen. Because nitrogen displaces oxygen without triggering the body’s normal suffocation reflex, proponents argued the method would cause rapid, painless unconsciousness.
The first nitrogen execution, in January 2024, complicated that claim. State attorneys had told courts unconsciousness would come within seconds, but witnesses reported the condemned person appeared conscious for several minutes, shaking and writhing for at least four minutes before breathing heavily for several more. The full process took roughly half an hour after the witness curtain opened. In October 2025, the Supreme Court declined to review a constitutional challenge to the method, and a second nitrogen execution proceeded the same day.
Firing Squad
Five states authorize the firing squad. In most of them it is a backup that activates only when lethal injection and other alternatives are unavailable. A small team of corrections staff with rifles fires simultaneously from a short distance at a target placed over the heart of the restrained, hooded condemned person. Protocols vary: some states use three shooters at 15 feet, older protocols have called for five shooters at greater distances. Death results from massive blood loss and destruction of the heart and is generally rapid compared to other methods. The firing squad has seen a legislative comeback driven almost entirely by drug shortages, since it depends on no pharmaceutical supply chain.
Hanging
Hanging remains on the books in a very small number of states but has not been used in the modern era and likely could not be carried out in practice. At least one state that once authorized it has already dismantled its gallows. Where it survives in statute, it is a last-resort fallback.
The method uses a “long drop” where the rope length is calculated from the person’s weight. Done correctly, the drop fractures the upper spine and severs the spinal cord, causing near-instant death. A rope too short causes slow strangulation; too long risks decapitation. The precision required, and the visibility of anything going wrong, are the main reasons hanging has been abandoned in favor of methods perceived as more clinical.
Why States Keep Adding Backups
The expansion of authorized alternatives is not driven by preference. Starting around 2010, major pharmaceutical manufacturers began refusing to sell their products for use in executions, and European export restrictions cut off the main supply of sodium thiopental. States turned to compounding pharmacies, switched drug combinations, and in some cases obtained drugs through channels that drew legal challenges.
More than a dozen states then enacted secrecy laws shielding the identity of drug suppliers, the specific drugs used, and the pharmacies compounding them. Courts have repeatedly been asked whether that level of secrecy violates due process, and most challenges have failed. Drug shortages are the single biggest reason states have expanded their lists of authorized backup methods: when lethal injection drugs cannot be obtained, states need a fallback already written into law.
How the Method Is Chosen in a Given Case
Each death-penalty state sets up a hierarchy of authorized methods by statute. The structure works as a cascade: the primary method applies unless a specific trigger activates the next one in line. The common triggers are:
- Drug unavailability, either because suppliers refuse to sell or a court has blocked the specific protocol.
- A court ruling striking down the primary method as unconstitutional, which activates the next authorized alternative.
- Inmate election. Some states let the condemned person choose an alternative within a set deadline, often 30 days after a state supreme court affirms the death sentence. Missing the deadline locks in the default.
A few states tie the available options to when the crime was committed. A person sentenced for an offense predating a statutory cutoff may still be eligible to choose a method (such as lethal gas or electrocution) that is no longer available to those convicted more recently. If no choice is made, lethal injection applies.
The cascade can run several layers deep. Some statutes authorize nitrogen hypoxia if lethal injection is unavailable, then electrocution if nitrogen hypoxia is also unavailable, then the firing squad if none of the preceding methods can be used. This stacking reflects the practical reality that drug shortages and ongoing litigation can take the primary method off the table with little warning.
Federal and Military Executions
The federal government and the U.S. military carry out death sentences independently of any state system. Federal law directs that a federal death sentence be implemented using the method prescribed by the state where the person was sentenced.1Office of the Law Revision Counsel. 18 U.S. Code 3596 – Implementation of a Sentence of Death If that state has no death penalty, the sentencing court designates a state that does, and that state’s method applies. In practice, the federal government has used a single-drug pentobarbital injection for its most recent executions. Thirteen federal executions took place between 2020 and 2021 after a nearly two-decade pause. A moratorium followed, and in January 2025, an executive order directed the Attorney General to “pursue the death penalty for all crimes of a severity demanding its use.”2The White House. Restoring the Death Penalty and Protecting Public Safety Military death sentences are carried out by lethal injection at the U.S. Disciplinary Barracks, the military’s maximum-security prison.
What the Constitution Requires of an Execution Method
The Eighth Amendment prohibits cruel and unusual punishment, and that prohibition applies to how a death sentence is carried out, not just whether it can be imposed.3Congress.gov. Constitution Annotated – Amdt8.4.9.10 Execution Methods The Supreme Court has never required that executions be painless. The question is whether a method inflicts gratuitous suffering beyond what the sentence itself demands, judged against what a 1958 decision called “the evolving standards of decency that mark the progress of a maturing society.”4Justia. Trop v. Dulles, 356 U.S. 86
Three modern Supreme Court decisions set the framework for challenging a method. Baze v. Rees (2008) upheld a three-drug lethal injection protocol and said a method violates the Eighth Amendment only if it creates a “substantial risk of severe pain” that is “objectively intolerable.”5Legal Information Institute. Baze v. Rees Glossip v. Gross (2015) added a procedural requirement: a prisoner challenging a method must identify a “known and available alternative” that would significantly reduce the risk of severe pain. Glossip upheld the use of midazolam, a less potent sedative that had replaced unavailable barbiturates.6Justia. Glossip v. Gross, 576 U.S. 863 Bucklew v. Precythe (2019) tightened the standard further, holding that the proposed alternative must be “feasible, readily implemented,” and shown to significantly reduce a substantial risk of severe pain, and that the state must have refused to adopt it without a legitimate correctional reason.7Supreme Court of the United States. Bucklew v. Precythe, 587 U.S. 119
The practical effect is that successful method challenges are extremely difficult. The prisoner bears the burden of essentially designing a better protocol, and must do so even when the state’s chosen method has caused visible problems in past executions.