Humane Execution Using Nitrogen



  1       Executive Summary

This paper seeks to advance the case for an alternative, viable, humane and certain means of administering capital punishment, with limited modification to prison death chambers already equipped for causing death by lethal injection[1].

The method proposed is to cause death of the condemned by hypoxia, using a standard clinical plastic face mask connected by a length of standard-gauge polythene tubing to a canister of Nitrogen gas. The Nitrogen gas canister would be housed, with its supply both initiated and regulated, from within the drugs room currently used to administer intravenous drugs during executions.

Visually, the proposed process will appear equally as clinical as existing lethal injection protocols.

Unlike old-style gas chambers, which used highly toxic Hydrogen Cyanide gas to bring about death, Nitrogen is ordinarily found in air and comprises 78% of the Earth’s atmosphere, it is non toxic and therefore the elaborate precautions necessary for the safety of correctional staff and witnesses presented by old-style gas chambers is wholly eliminated.

The technology for causing death by Nitrogen hypoxia is basic, readily available and the cost of converting any death chamber equipped for lethal injection is probably less than $400 per facility.

This paper does not make, nor does it seek to make, any moral or ethical judgement about the use of capital punishment, nor does it deal with any alleged deterrent or other effect of its use. Instead, this paper advocates that where States have legislation in place for the application of the death penalty, that executions are conducted in a humane and constitutional manner[2]. Death is determined when signs of respiration, cardiac activity and brain activity are extinct. These signs are not necessarily co-terminus. This paper therefore recognises that human death is therefore a process, rather than a single event.


2        Existing Methods of Execution in the United States


a)      Lethal Injection – Each participatory State will have its own protocol for execution by lethal injection.  In essence however, protocols are all very similar.  In preparation for the execution, the condemned is strapped to a fixed gurney in the death chamber. A clinician then inserts a medical cannula into a vein in either the arm or the groin of the condemned and this in turn is connected to a saline line, which leads through a small aperture to an adjoining room equipped with syringes containing lethal drugs. A second adjoining room, with viewing window into the death chamber, is provided for witnesses.  After the death warrant is read to the condemned, he or she is given an opportunity to make a final statement and then a signal is given for the sequential flow of drugs to commence. When first introduced, many States opted to use a combination of drugs[3] which initially sedated the condemned, before subsequently paralysing muscles and seizing the heart (sometimes  anti-histamine is administered prior to the execution to prevent the condemned involuntarily producing foam at the mouth during the execution). The supply of drugs available for use in executions, particularly Sodium Thiopental, has however become restricted in recent years, with many companies reluctant to supply correctional institutions – and entire blocks of Countries banning export of materials used for the application of the death penalty[4].  Other combinations of drugs have been used on an experimental basis for executions, including Midazolam in combination with Hydromorphone[5].  As a result of a contracting supply of the initially preferred drug combinations, some States[6] have advocated the use of a single drug, administered in large quantity to secure a swift death. The influential bi-partisan Constitution Project published a 200 page report[7] highlighting concerns with the use of three-drug protocols, which it contends “poses a risk of avoidable inmate pain and suffering”. There is however no overall cohesion with regard to either choice or use of drugs across the USA and many challenges as to constitutionality continue to be pursued, particularly following reports of ‘botched’ or incomplete executions[8].



b)      Electric Chair – First used in New York State in 1890 and thereafter widely adopted throughout the USA[9], the method relies upon the death chamber[10] being equipped with a large, fixed wooden chair, into which the condemned is strapped at each limb and over the torso, lap and head.  In preparation for execution, the condemned has a patch of hair shaved from his or her scalp and another patch of hair shaved from his or her leg(s) to allow good electrical contact between the skin and the execution apparatus. Having been strapped into the chair, metal electrodes, lined with saline-soaked natural sponge, are strapped to the head and leg(s) of the condemned.  From within the death chamber, or an alcove nearby, cycles of electricity are then applied to the condemned until death is certified by the attending physician. It is believed that when competently administered, unconsciousness occurs during the first massive jolt of electricity. Death by electrocution is subsequently brought about by a combination of the heating effect of the electrical current upon internal organs to a point above which life cannot be sustained, coupled with seizure of the condemned’s heart, causing a cardiac arrest. There may also be an element of asphyxiation caused by paralysis of the lungs due to electrical interference with natural muscle rhythm. When first introduced, the executioner had to use his subjective judgement and expertise to manually control the flow of electricity using both a switch and variable rheostat to cause death; but in newer apparatus, both the immensity and the duration of the sequential charges is automatically controlled within the equipment, after the system is triggered[11]. Eight States retain an electric chair as an alternate method to lethal injection[12]


c)       Hanging – One of the oldest methods for administering capital punishment. In essence, a slip-noose of rope is placed around the neck of the condemned and the entire weight of the condemned’s body is thereafter suspended from the resulting ligature. Depending on the method[13] of suspension, death occurs by either strangulation, fatal spinal injury resulting from a fracture dislocation of the neck vertebrae or actual decapitation.  A number of methodologies have been applied over the centuries to accomplish death by hanging.  In primitive times, the condemned, with noose around his or her neck was simply pushed off a stool, a ladder or the rear of a cart and left to suffer death by slow strangulation. This system eventually became replaced by the use of a trapdoor, through which the condemned fell.  Advances to trap-door hanging were subsequently made in Victorian England by its then Hangman William Marwood[14].  By placing the knot of the noose below the prisoner’s left jaw bone, Marwood developed the principle of the variable ‘long drop’, whereby the length of the rope is adjusted in inverse proportion to the bodyweight of the condemned.  Lighter prisoners were given a longer ‘drop’ and heavier prisoners a shorter ‘drop’.  His principle ensured that after the prisoner fell through the trapdoor, the stopping of the body’s fall by a sudden jolt at the end of the rope caused both near-instantaneous unconsciousness and a fatal fracture of the neck vertebrae as the condemned’s head was thrust violently backwards. The variability of the drop was intended to avoid the unacceptable extremes of either decapitation or slow strangulation. A further variation could be found in Eastern Europe. The Austro-Hungarian method of hanging (pole hanging)[15] involved the condemned being hoisted up a pole by means of an under-arm harness, with a long rope being firstly tied to the legs.  While hoisted by the harness, a noose of short length is fixed from the top of the pole and placed around the neck of the condemned.  Moments later the harness is released, causing the condemned to fall a short distance, while assistant executioners pulled on the condemned’s leg ropes, in order to shorten the strangulation process. Several US States provide for the death penalty to be conducted by hanging using a trapdoor and drop[16].


d)      Gas Chamber – The use of toxic gas for the purpose of judicial execution was first used in the US by the State of Nevada in 1924. Since that time a number of other States[17] adopted its use and purchased gas chambers from their principal manufacturer[18]. The method uses a specially fabricated, air-tight steel chamber, with a single entrance door. The chamber has a fixed chair in which the condemned is restrained and several windows to allow a view of the execution procedure by witnesses. The top of the chamber is equipped with an exhaust fan and chimney flue in order to vent residual gas into the atmosphere after an execution. Prior to an execution, a correctional officer places a quantity of Potassium Cyanide pellets in a cloth bag which is suspended beneath the gas chamber chair. The condemned, fitted with a special vest which incorporates a stethoscope is then led to the chamber and strapped into the chair. A rubber tube is connected to the vest stethoscope to allow a physician to monitor the condemned’s heartbeat from outside the chamber. The correctional staff withdraws and seal the gas chamber door closed.  A quantity of Sulphuric Acid is then released from a vessel outside the chamber, through a pipe that leads into a tray situated under the gas chamber chair.  The extraction fan is turned on to maintain a negative pressure within the chamber and prevent leakage of toxic gas. On a signal from the Warden a lever is moved, which lowers the bag of Potassium Cyanide pellets into the tray containing Sulphuric Acid.  A chemical reaction occurs, releasing a cloud of lethal Hydrogen Cyanide[19] gas, which fills the chamber and brings about death of the condemned though asphyxia[20]. The gas is said to smell like bitter almonds.  After death has been confirmed by the physician monitoring the heartbeat, the naked cadaver and interior of the chamber are sprayed with an Ammonia solution to neutralise any remaining toxins present.  The condemned’s clothing has to be burned as it will be highly toxic from exposure to the gas. Several States retain gas chambers as a secondary method to lethal injection.[21]


e)      Firing Squad – In its simplest form, any facility such as a prison warehouse can be adapted for execution by firing squad. Typically a sturdy chair is set against a wall which has been lined with sandbags. The chair is equipped with leather restraints for limbs and torso. Twenty or so feet in front of the chair a canvass screen is erected with several apertures at around 5 feet from the ground.  The condemned is escorted to the chair, the restraints fastened and a blindfold applied.  The attending physician identifies the precise location of the condemned’s heart and pins a white target at that location.  Several marksmen, equipped with loaded rifles stand behind the canvas screen. One of the guns is loaded with a blank round. At a signal from the warden, the marksmen take aim at the target through the apertures in the canvas screen and simultaneously fire. Death is brought about by cardiac arrest and massive haemorrhage. Two States retain the availability of firing squad as an alternate method of execution.[22]



3        Issues & Concerns with Existing Execution Methods


There have been a number of concerns with existing methods.  Use of electrocution has on occasion caused extensive burns[23] to the condemned and more than one application of current to cause death[24].  The gas chamber is inherently dangerous to those who operate it, requiring great care to maintain air-tightness of the chamber and the need for both the chemicals used in the execution and the clean-up process to be handled with extreme caution. Furthermore, witnesses have testified to extreme suffering of the condemned, with death not occurring for up to 11 minutes after the gas cloud is generated[25]. Firing Squad executions cause excessive trauma to the condemned and hanging can result in incomplete fracture dislocation of the neck vertebrae, causing a painful death by strangulation. Use of lethal injection has caused problems[26] not only with the availability of suitable drugs[27] but also failure to insert the cannula needle completely into a vein, causing instead intramuscular administration of the drugs and a prolonged death[28]



4        Use of Nitrogen in Executions

Surprisingly, no Country has yet used Nitrogen as a method of execution. The air we breathe comprises approximately 78% Nitrogen, 21% Oxygen and 1% of minor inert gases. Human lungs have evolved to extract Oxygen from air and through the natural process of breathing.  Nitrogen is colourless and odourless. Each year a number of accidental deaths are reported where humans accidentally stray into a Nitrogen-rich environment, fail to notice, become drowsy, quickly lose consciousness and thereafter expire[29].

A human breathes around 15 times a minute.  Unconsciousness in accidental Nitrogen asphyxia occurs in less than 1 minute[30]. In the modified atmosphere of the clinical mask, an Oxygen concentration reduced to 4% to 6% – through displacement by Nitrogen -will result in loss of consciousness in less than 40 seconds, [31] and death occurring a few minutes later.  In a pure Nitrogen environment, loss of consciousness and subsequent death would be even quicker.  It is contended[32] that unconsciousness occurs both painlessly and without the distressing feeling of suffocation which occurs with other forms of hypoxia as the body is used to existing in natural atmospheric air which is 78% Nitrogen in any event.

The cost of equipping a death chamber for a Nitrogen execution would be minimal, by utilising the gurney and existing room formats currently used for lethal injection executions. The only additional apparatus needed would be the clinical mask, a length of polythene tubing and a canister of Nitrogen. Unlike lethal injection, no medical training is necessary, with the sole requirement for the presence of a physician being for the purpose of certifying death.

It is suggested that use of a standard plastic surgical mask (of the type used in hospitals for provision of oxygen to patients) would be an effective method of delivering a pure Nitrogen  or  Nitrogen-rich mix to the condemned, thereby quickly and painlessly  inducing unconsciousness before causing death by hypoxia. The flow of Nitrogen would be initiated and regulated from the room adjoining the death chamber, currently used for administering drugs.

Unlike the elaborate procedures needed to safeguard correctional officers and witnesses with old-style gas chambers using highly toxic Hydrogen Cyanide, the use of Nitrogen poses no risk to those in attendance within the death chamber, as any leakage from the face mask would harmlessly diffuse into the 78% of Nitrogen ordinarily present in atmospheric air.  Nitrogen canisters are widely available from a variety of sources.


5        Conclusion

For the reasons set out in this paper, the use of Nitrogen provides a humane, certain and effective manner of execution.


9th May 2014.





Kevin J O’Keefe LLB (Hons), 

Solicitor of the Supreme Court of England & Wales.




[1] The term ‘lethal injection’ is used in the context principally of US correctional facilities where the death chamber is equipped with a fixed gurney and where there are adjoining rooms for the accommodation of witnesses and for drug administration.

[2] The Eighth Amendment of the US Constitution prohibits the use of cruel or unusual punishments.

[3] Initially the drugs used were Sodium Thiopental, Pancuronium Bromide (Pavulon) and Potassium Chloride.

[4] Within the USA, Hospira Inc halted the production of Sodium Thiopental for death penalty usage. The United Kingdom subsequently banned export of Sodium Thiopental for use in executions in December 2010 and on the 21 December 2011, the entire European Union banned export of many chemical compounds that could be used for application of the death penalty, citing European Union Regulation No. 1236/2005 – “Products used for Capital Punishment and Torture”. The dilemma is explored in greater detail in “Lethal Injection Chaos Post-Baze” by Deborah W.Denno of Fordham Law School, 13th  November 2013 – Research paper 2328407.

[5] The State of Florida used Midazolam and Hydromorphone on 15 October 2013, followed by the State of Ohio using a similar combination a month later.

[6] Ohio used Sodium Thiopental as a single drug on 8 December 2009 and thereafter Pentobarbital in a one drug protocol on 10 March 2011.  This has been followed by Arkansas, Georgia, Missouri, South Dakota & Texas. Several other States have indicated a willingness to follow suit.

[7] Report published on 7th May 2014 by

[8] See footnotes 23 to 25 later.

[9] And in the Philippines until 1976

[10] Note that some Southern States used a portable electric chair in the 1940’s & 1950’s that was taken from county to county, rather than located in a single static death chamber location.

[11] Initial contact is usually made at around 2,250 volts and thereafter reduced to 500 volts at approximately 6 amperes, with the sequence repeated at intervals over several minutes.

[12] Alabama, Arkansas, Florida, Kentucky, Oklahoma, South Carolina, Tennessee & Virginia.

[13] Historically, a noose was placed around the neck of the condemned and then the execution was completed by the condemned being hoisted into the air by pulling at the other end of the rope. Over the years modifications were made for a ‘short drop’ or ‘standard drop’ whereby the condemned, having stood with arms and legs strapped together on a trapdoor was dropped by a standard length of 5 feet or so.  For those condemned of slight weight, the method would result in death by slow strangulation.  For those of heavy weight, death would result by actual decapitation. For those of a fortunate to be of optimum weight, death would result from an immediate fracture dislocation of the neck vertebrae.

[14] 1820-1883

[15] See YouTube (CAUTION : graphic video – viewer discretion advised)

[16] Delaware, New Hampshire & Washington as a secondary method to lethal injection.

[17] Colorado, Arizona, North Carolina, Wyoming, California, Missouri, Oregon, Mississippi, Maryland & New Mexico.

[18] Eaton Metal Products Inc. of Denver, Colorado.

[19] Sometimes known as Hydrocyanic gas

[20] Inhalation of Cyanide prevents the blood of the condemned from absorbing Oxygen, resulting in asphyxia.

[21] Arizona, Missouri & Wyoming.

[22] Oklahoma & Utah.

[23] The execution of Jesse Tafero at Raiford State Penitentiary, Florida on 4th may 1990 resulted in six-inch flames shooting from the head of the condemned as the current was applied.

[24] Willie Francis execution by electrocution on 3rd May 1946 was incomplete. He was granted a stay and ultimately executed on the State of Louisiana’s second attempt, a year later on 9th May 1947. On 14th July 1989 in the State of Alabama, the cables leading to the electric chair were improperly connected. It took several jolts of electricity over a period of 19 minutes for Horace Dunkins Jr to be pronounced dead.

[25] See State of Arizona’s execution of Donald Eugene Harding on 6th April 1992 where death was not pronounced for 11 minutes after the lethal Hydrogen Cyanide gas was released – and a similar timeframe in the State of California’s gas chamber execution of Robert Alton Harris at San Quentin on 21st April 1992.

[26] See footnote 7 earlier.

[27] See footnote 4 earlier.

[28] The recent case of Clayton Lockett in Oklahoma, where the condemned died 1 hour and 44 minutes after he was first restrained on the gurney.  It is believed that the cannula pierced through his vein, causing the drugs to be inadvertently administered into surrounding soft body tissue, rather than directly into his circulatory venal system.

[29] Around 12 accidental Nitrogen deaths are reported in the USA each year – “Hazards of Nitrogen Asphyxiation” – US Chemical Safety and Hazard Investigation Board – 11th June 2003. For example in 1981 two NASA technicians lost consciousness when exposed to Nitrogen in the vicinity of a Space Shuttle. One subsequently died.  In 1999 a Scottish Laboratory worker died of Nitrogen hypoxia, when liquid Nitrogen was spilt onto the floor of a stockroom.

[30] In aircraft flying above 30,000ft, a sudden decompression, causing low oxygen levels in ‘thin air’ can cause pilots to lose consciousness so swiftly that they cannot even react to the event.

[31] “Forensic Pathology” 2nd Edition. Chapter 8 by V.J Di Maio

[32] “Killing with Kindness – capital punishment by Nitrogen asphyxiation” – National Review – 11 October1995 – S A Creque




  • “Lethal Injection Chaos Post-Baze” – by Deborah W.Denno of Fordham Law School, 13th November 2013 – Research paper 2328407.
  • Executioner Pierrepoint (1974) Harrap – reprinted in 2005 – Dobby.
  • “Agent of Death, Memoires of an Executioner” (1940) RG Elliott & AR Beatty
  • “I Killed for the Law” – Leo Sheridan (1938) Stackpole & Sons
  • The Execution Protocol” (1995) Stephen Trombley
  • European Union Regulation No. 1236/2005 – “Products used for Capital Punishment and Torture”.
  • Effect of Rapid Decompression and Associated Hypoxic Phenomena in Euthanasia of Animals – A Review” – Nicholas M Booth DVM, PhD
  • Report “Irreversible Errors”  published on 7th May 2014 by
  • YouTube
  • “Forensic Pathology” – 2nd Edition – Chapter 8 by V.J Di Maio
  • “Fourteen Days in May” BBC television documentary – Directed by Paul Hamann (1987)
  • “The Science of Killing” BBC television documentary – 15th January 2008.
  • International Humanitarian Nitrogen Hypoxia Project –
  • Inert gas asphyxiation –