United Nations experts on Wednesday called on US authorities not to go ahead with the planned execution of an inmate by nitrogen hypoxia, saying the method may subject him to "cruel, inhuman or degrading treatment or even torture."
Kenneth Smith, convicted for a murder-for-hire committed in 1988, is scheduled to be executed in the US state of Alabama on January 25 using the method, which is intended to deprive him of oxygen by using a face mask connected to a cylinder of nitrogen.
Nitrogen hypoxia execution leads to painful death
Smith, 58, is one of only two people alive in the US to have survived an execution attempt after Alabama botched his previously scheduled execution by lethal injection in November 2022 when multiple attempts to insert an intravenous line into a vein failed.
"This will be the first attempt at nitrogen hypoxia execution," four UN special rapporteurs said in a statement, saying the method could cause "grave suffering" and likely be at odds with the prohibition on torture and other cruel, inhuman, or degrading punishment.
"We are concerned that nitrogen hypoxia would result in a painful and humiliating death."
Execution may be a violation of US Constitution
Smith's lawyers have said the untested gassing protocol may violate the US Constitution's ban on "cruel and unusual punishments" and have argued a second attempt to execute him by any method is unconstitutional.
Most US executions are carried out using lethal doses of a barbiturate, but some states have struggled to obtain the drugs because of a European Union law banning pharmaceutical companies from selling drugs that can be used in executions to prisons.