Which U.S. states have legislated nitrogen hypoxia or gas‑chamber options for executions, and what did their bills say?
Executive summary
Several states have written nitrogen hypoxia or more generalized “lethal gas” options into law or into proposed bills; Alabama, Oklahoma and Mississippi are among the earliest adopters on the books, Alabama is the only state that had developed a protocol and used nitrogen hypoxia, and a second wave of bills—Louisiana (enacted), Ohio, Nebraska, Arkansas, Indiana and others—have sought to add nitrogen or gas options often without detailed protocols, leaving implementation to corrections departments [1] [2] [3] [4] [5] [6] [7].
1. Which states currently authorize nitrogen hypoxia or lethal gas, and how those laws read
Alabama’s statute explicitly authorized nitrogen hypoxia as an option and the state became the first to execute a person using nitrogen by mask, after developing a heavily redacted protocol; Alabama has framed the method as an alternative when lethal injection is unavailable, and the state’s adoption has been followed by new enforcement activity and litigation [8] [3] [9]. Oklahoma added nitrogen hypoxia to its statutes in 2015 and at times designated it as a fallback or primary method if lethal‑injection drugs were unavailable, although the state later deferred active use while exploring protocols [1] [6]. Mississippi’s legislature adopted a nitrogen hypoxia authorization in 2017, placing the method on the statutory list of execution options even though it had not been used there before Alabama’s executions [2]. Several other states historically authorize “lethal gas” more generally—Wikipedia’s compilation lists Alabama, Arizona, California, Mississippi, Missouri, Oklahoma and Wyoming as states that authorize lethal gas under specified circumstances—which in some statutes means a gas option exists if lethal injection is unavailable, the prisoner chose gas, or the crime predates a certain cutoff [1].
2. Recent enactments and near‑enactments: Louisiana, Arkansas, Ohio, Nebraska, Indiana
Louisiana’s 2024 law (often cited as HB6/SB 430 in reporting) expressly added nitrogen gas to its roster of methods and was signed by Gov. Jeff Landry; the legislative push came after Alabama’s use and was intended to restart executions in a state that had paused them—reporting shows the bill passed the legislature though a later House committee vote on a related measure failed in 2025 coverage [4] [10] [11]. Arkansas saw a bill pass its House that would add nitrogen gas as an alternative method but left how to administer nitrogen (mask vs. tent/chamber, concentration, and protocol details) to the Department of Corrections; critics flagged that silence as a major gap [6] [12]. Ohio and Nebraska lawmakers introduced measures to authorize nitrogen hypoxia after Alabama’s actions—Ohio’s sponsors publicly announced a bill to permit nitrogen hypoxia as an option where lethal injection is unavailable and sought support from state officials, while Nebraska’s legislature considered similar proposals [5] [13]. Indiana’s House committee advanced House Bill 1119 to add nitrogen hypoxia (and firing squad) to execution options alongside lethal injection, though a companion Senate effort previously stalled [7].
3. What the bills actually specify — method, fallback status, and delegation to corrections
A consistent pattern across these statutory efforts is modest specificity: some laws name “nitrogen hypoxia” expressly (Mississippi, Oklahoma, Alabama, Louisiana), others retain a generic “lethal gas” option or allow gas if lethal injection is unavailable or if an inmate elects it; several more recent bills intentionally leave operational details—delivery method, concentration, sealing, or protocol—to corrections officials, which critics say makes the statutes hollow on safety and oversight [1] [2] [4] [6]. Alabama is the exception in practice: it produced an execution protocol (largely redacted) and carried out executions using a mask, which has generated accounts of secrecy and contested witness descriptions [3] [11].
4. Competing claims, industry resistance, and legal context
Proponents have framed nitrogen hypoxia as a practical, “humane” alternative when lethal‑injection drugs are scarce; sponsors in Indiana and Ohio publicly argued for modernization and reliability [7] [5] [8]. Opponents—human‑rights groups, medical experts, religious leaders and some legislators—contend the method is experimental, potentially cruel, and accompanied by dangerous operational risks to staff and by secrecy in protocols [2] [11] [9]. Commercial resistance has also shaped the landscape: at least three of the largest U.S. nitrogen suppliers have publicly barred sales for executions, complicating states’ ability to source medical‑grade gas even where statutes authorize it [10] [13].