Nitrogen gas is the just latest method in America’s long quest for a pain-free execution

A group gathered at the state capitol building in Montgomery, Alabama to stop the planned execution of Kenneth Eugene Smith
A group gathered at the state capitol building in Montgomery, Alabama to stop the execution of Kenneth Eugene Smith - Mickey Welsh

Reading about the execution of Kenneth Eugene Smith one cannot help feeling shocked by the gory details.

After being secured to a gurney in the death chamber, the convicted murderer – who on Friday became the first ever person to be put to death with nitrogen gas – had a tightly fitting mask strapped to his head. Eye witnesses reported that as the nitrogen began to flow from its pressurised metal container, Smith writhed and thrashed violently on the gurney, panting loudly and attempting to hold his breath. He was pronounced dead 22 minutes later.

In recent years, shortages of lethal injection drugs caused by pharmaceutical companies restricting their sales to prison agencies have encouraged certain states to look for new ways of administering the death penalty, with Alabama, Oklahoma and Mississippi permitting Nitrogen gas as an alternative since 2022. America’s mission to crack pain-free execution has been ticking over for decades, harking back to the electric chair. Kenneth Eugene Smith was its latest experiment.

Kenneth Eugene Smith became the first ever person to be put to death with nitrogen gas
Kenneth Eugene Smith became the first ever person to be put to death with nitrogen gas - Getty

For better or worse, devising new and creative ways to kill one another has been a source of ceaseless innovation throughout human history. The Ancient Persians were known to have plunged condemned people into a room full of stirred-up ash, causing them to suffocate. Meanwhile, the Greek ruler Phalaris supposedly forced his victims to climb inside a bronze sculpture of a bull before roasting them alive. But the Romans were the masters of coming up with extravagant execution techniques, from crucifixion to burying alive and throwing their enemies from a cliff in the case of Emperor Tiberius.

But in the 17th Century age of the Enlightenment – that great melting pot of scientific ideas that did away with the Roman calendar and devised the metric system – humanist ideas about the notion of dignity emerged and with them, calls for more reliable, less brutal forms of capital punishment. These are the ways in which the death penalty has evolved throughout the centuries.

Beheading by axe and sword

Beheading was widely used throughout Europe during the Middle Ages. It was most commonly practised with a sword for nobility and an axe for commoners. However, it proved an inefficient and sometimes messy means of getting the job done. It famously took up to eight blows of the axe to chop off the head of the Duke of Monmouth who was put to death by James II, while Mary Queen of Scots was subjected to three separate blows after she rebelled against Queen Elizabeth I.

Beheading was gradually phased out during the Renaissance and Enlightenment periods in Britain, with the method reserved for nobility. Meanwhile in France, the arrival of the guillotine in the late 18th Century put the old swordsmen out of business.


Hanging was the most widespread form of capital punishment in Britain from the Anglo-Saxon era onwards. Following opposition to the brutality of the practice from the likes of Charles Dickens, the more humane long-drop gallows was invented in the late 19th century. The new method considered the weight of the condemned and the length of the drop to ensure their neck was broken, which was deemed quicker and less painful than strangling.

The art of the long-drop was perfected by Albert Pierrepoint, Britain’s most prolific 20th-century hangman. Pierrepoint executed more than 430 people and prided himself on limiting the time between entering the condemned man’s cell and opening the trapdoor to a maximum of 12 seconds.

The last hanging to take place in Britain was in 1964, while the final hanging to take place in the US was in Delaware in 1994. Today, New Hampshire is the only US state that permits hanging as a method of execution.

Alabama's lethal injection chamber at Holman Correctional Facility
The lethal injection chamber at Holman Correctional Facility in Alabama: Lethal injection has been the most common method of execution in the US since the 1970s - Dave Martin

The guillotine

The guillotine wasn’t actually invented by Joseph-Ignace Guillotin at all, but rather by a harpsichord manufacturer called Tobias Schmidt. However, Guillotin proposed the device in a periodical as “a machine that beheads painlessly”, and it proved so popular following its first usage in 1792 that his name quickly became associated with it. During the French Revolution, up to 17,000 people were guillotined in France and its use continued well into the 20th Century, with the last such execution taking place in 1977.

The electric chair

Invented in 1881 by a New York-based dentist, the electric chair became synonymous with the death penalty in the US and involves strapping the condemned to a specially designed wooden chair and sticking electrodes to the head and legs.

Originally designed as a humane alternative to hanging, the electric chair has been in decline since the 1970s following a series of botched executions in which those convicted had to be electrocuted multiple times. As of 2024, the only states that still offer the electric chair as an option for execution are Alabama, Florida, Kentucky, Tennessee, Mississippi, Arkansas and Oklahoma.

The gas chamber

Since 1976, 11 executions by gas chamber have been conducted in the US using hydrogen cyanide gas, the last of which took place in Arizona in 1999.

Firing squad

Firing squad has been one of the most common methods of execution since firearms came into common use. Joseph Stalin sentenced more than one million Soviet citizens to death by a bullet to the back of the head during the Great Purge. Meanwhile in China, Chairman Mao claimed that 800,000 people were executed by firing squad during the Cultural Revolution. Following a shortage of lethal injection drugs in the US, a string of American states have adopted the firing squad including South Carolina, Oklahoma, Mississippi and Idaho, though Utah remains the only state to have actually used the method in the past century.

Lethal injection

Lethal injection has been the most common method of execution in the US since the 1970s with sodium thiopental and Pentobarbital the most common choice of drug. Around 1,400 people have been given the lethal injection in the US in total, but in recent years international boycotts led by the UK and European governments, along with pharmaceutical companies, have led to states scrambling for other ways to execute prisoners.

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