Execution methods by state fall into a clear pattern: all 27 states that currently authorize capital punishment, along with the federal government and the U.S. military, use lethal injection as the primary method, and a smaller group of states also authorize electrocution, firing squad, nitrogen hypoxia, or lethal gas as either an inmate’s choice or a statutory fallback. The alternatives exist mainly because drug shortages and litigation have made lethal injection unreliable, not because states prefer them.
Lethal Injection: The Universal Primary Method
Every death-penalty jurisdiction in the United States authorizes lethal injection, and most designate it as the sole or default method. Federal executions are governed by 28 CFR Part 26, which directs the Bureau of Prisons to administer a lethal quantity of a substance chosen by its director,1eCFR. 28 CFR Part 26 – Death Sentences Procedures under the authority of 18 U.S.C. ยง 3596.2Office of the Law Revision Counsel. 18 USC 3596 – Implementation of a Sentence of Death
State drug protocols generally follow one of two models. Some states use a single-drug protocol, typically a large dose of pentobarbital that causes death by anesthetic overdose; Georgia, Texas, and Arizona take this approach. Others use a three-drug sequence combining a sedative such as midazolam or etomidate, a paralytic like rocuronium bromide, and a heart-stopping drug such as potassium chloride or potassium acetate. Alabama, Arkansas, and Florida use variations of the three-drug method.
These protocols are written by corrections departments through administrative rules rather than by legislatures, which lets prison officials change drugs without new laws but also means the specific chemicals used can shift with little public notice. To protect their supply chains, at least 14 death-penalty states have enacted secrecy laws shielding the identity of drug suppliers.
Electrocution
The electric chair is authorized in several states, always alongside lethal injection rather than as a standalone method.
- Alabama. Inmates may choose electrocution in writing within 30 days after the Alabama Supreme Court affirms the death sentence. Lethal injection is the default if no choice is made.3Alabama Legislature. Alabama Code 15-18-82.1 – Methods of Execution, Election of Method, Constitutionality
- Florida. Inmates may choose electrocution in writing within 30 days after the Florida Supreme Court issues its mandate affirming the sentence. Lethal injection applies if no election is made.
- Kentucky. Inmates whose offense predates March 31, 1998, may choose electrocution. If no choice is made at least 20 days before the scheduled execution, lethal injection applies.
- Tennessee. Inmates whose offense predates January 1, 1999, may choose electrocution. It also applies automatically if lethal injection is ruled unconstitutional or if the corrections commissioner certifies that injection drugs are unavailable.4Justia. Tennessee Code 40-23-114 – Death by Lethal Injection
- South Carolina. Electrocution became the default method in 2021 after the state was unable to obtain lethal injection drugs for years. Inmates may alternatively choose lethal injection (if drugs are available) or firing squad.5South Carolina Legislature. 2021-2022 Bill 200 – Executions
- Arkansas and Mississippi. Both authorize electrocution as a backup behind lethal injection. In Mississippi, the corrections commissioner has discretion to pick from four authorized methods.6Mississippi Department of Corrections. Death Penalty in Mississippi – Federal and State Law
Firing Squad
Five states currently authorize execution by firing squad, and four expanded or added that authorization within the last decade in response to lethal injection drug shortages.
- Utah. The firing squad applies when lethal injection drugs are unavailable at least 30 days before a scheduled execution, when a court rules the inmate has a right to it, or when lethal injection is held unconstitutional. Inmates sentenced before May 3, 2004, may also choose it outright.7Utah Legislature. Utah Code 77-18-113 – Judgment of Death – Method Is Lethal Injection – Exceptions for Use of Firing Squad
- Idaho. The corrections director must certify within five days of a death warrant whether lethal injection drugs are available. If the director cannot certify availability or fails to file the certification, the method switches automatically to firing squad.8Idaho State Legislature. Idaho Code 19-2716 – Methods of Execution
- South Carolina. Added the firing squad in 2021 as one of three options alongside electrocution and lethal injection.5South Carolina Legislature. 2021-2022 Bill 200 – Executions
- Oklahoma. The firing squad is a tertiary fallback, authorized only if both lethal injection and nitrogen hypoxia are held unconstitutional or unavailable.9Justia. Oklahoma Code 22-1014 – Manner of Inflicting Punishment of Death
- Mississippi. Listed among four authorized methods, with the corrections commissioner selecting for each execution.6Mississippi Department of Corrections. Death Penalty in Mississippi – Federal and State Law
Nitrogen Hypoxia
Nitrogen hypoxia is the newest authorized method, and only three states allow it. The concept involves delivering pure nitrogen through a mask to displace oxygen, causing death by oxygen deprivation. Because the method does not depend on pharmaceutical supplies, it has attracted interest from legislatures frustrated by drug procurement problems.
- Alabama. Nitrogen hypoxia is one of three authorized methods. Inmates can elect it in writing within 30 days after the state supreme court affirms the sentence, using the same window available for choosing electrocution.3Alabama Legislature. Alabama Code 15-18-82.1 – Methods of Execution, Election of Method, Constitutionality
- Oklahoma. Nitrogen hypoxia is the secondary method if lethal injection is held unconstitutional or becomes unavailable.9Justia. Oklahoma Code 22-1014 – Manner of Inflicting Punishment of Death
- Mississippi. One of four authorized methods alongside injection, electrocution, and firing squad, with the corrections commissioner selecting the method.6Mississippi Department of Corrections. Death Penalty in Mississippi – Federal and State Law
Alabama carried out the first nitrogen hypoxia execution in January 2024, putting Kenneth Smith to death. State attorneys had assured courts that the method would render someone unconscious within seconds, but witnesses reported that Smith appeared conscious for several minutes after nitrogen flow began, shaking and writhing for at least four minutes before his breathing slowed. He was pronounced dead roughly 32 minutes after the curtains opened. The corrections commissioner stated that nitrogen flowed for approximately 15 minutes.
Justices Sotomayor, Kagan, and Jackson have flagged Eighth Amendment concerns about the mask-based delivery system in recent opinions, citing risks of incomplete oxygen displacement, conscious suffocation, and aspiration. The Department of Justice has defended the method, citing Fifth Circuit findings that breathing pure nitrogen causes unconsciousness in less than a minute with death following in 10 to 15 minutes.
Lethal Gas
Traditional lethal gas, using hydrogen cyanide, has largely fallen out of active use but remains on the books in a few states. Arizona allows inmates sentenced before November 15, 1992, to choose lethal gas over injection. Missouri also authorizes it, though the statute is ambiguous about whether the inmate or the corrections director makes the selection.
California’s lethal gas protocol was struck down by a federal court in 1994 as cruel and unusual punishment, a ruling upheld by the Ninth Circuit in 1996.10CDCR. History of Capital Punishment in California The state’s penal code still references lethal gas, but the judicial invalidation removed it as an option. California’s broader death penalty moratorium, in place since 2019, makes the question academic for now.
Hanging is no longer authorized in any U.S. state. It was once the dominant method, but the last states to authorize it have either replaced it or abolished the death penalty.
States That Do Not Carry Out Executions
Twenty-three states and the District of Columbia have abolished capital punishment. Michigan was first in 1847, followed by Wisconsin in 1853 and Maine in 1887. More recent abolitions include Colorado (2020), Virginia (2021), and Washington (2023).11Death Penalty Information Center. State by State In these jurisdictions the statutes authorizing executions have been repealed, so no method is available.
A separate group of states retain the death penalty but have halted executions through gubernatorial order. California, Oregon, Ohio, and Pennsylvania all have active moratoria. In these states, lethal injection protocols and legal authority remain intact, but no executions proceed while the moratorium is in effect. California’s moratorium dates to 2019. A future governor can lift any of these without legislative action.
New Hampshire is an unusual case. The state repealed its death penalty in 2019, but the repeal was not retroactive, leaving one person on death row.12Death Penalty Information Center. New Hampshire The authorized method before repeal was lethal injection, which would still apply to that individual’s sentence. Legislative efforts to reinstate the death penalty have been introduced but have not passed as of early 2026.
Why Method Challenges Rarely Change the List
The set of authorized methods stays remarkably stable even when specific executions go badly, because the constitutional test is hard to satisfy. The Supreme Court established the current standard through Baze v. Rees (2008), Glossip v. Gross (2015), and Bucklew v. Precythe (2019). A challenger must prove that the method poses a substantial risk of severe pain compared to known alternatives, and must identify a feasible alternative method that would significantly reduce that risk.13Justia. Glossip v Gross, 576 US 863 (2015) The second requirement is where most challenges collapse: the condemned person effectively has to propose a better way for the state to carry out the death sentence. Drug secrecy laws add another layer, because when states conceal what they are using, challengers struggle to build the factual record the standard demands.