The UN High Commissioner for Human Rights, Volker Türk, called on Alabama state authorities Tuesday to cancel the execution of Kenneth Eugene Smith, which is scheduled to take place next week by nitrogen hypoxia. Türk reemphasized human rights concerns regarding the potential consequences of the untested execution method.

According to the statement, execution by nitrogen hypoxia “could breach the prohibition on torture or other cruel, inhuman, or degrading treatment or punishment, as well as [Smith’s] right to effective remedies.” It references the Covenant on Civil and Political Rights and the Convention Against Torture and Other Cruel, Inhuman or Degrading Treatment or Punishment, both treaties to which the US is a bound party.

The statement also cites guidelines from the American Veterinary Medical Association (AVMA), which recommend that sedatives be delivered to animals being euthanized prior to a euthanizing agent, such as nitrogen. The AVMA explains that “this method will reduce [the animal’s] natural tendency to breath-hold when confronted with unpleasant odors” and other “potential aversion responses.” The UN contrasts these recommendations with Alabama’s execution protocol, which “makes no provision for sedation of human beings prior to execution.” The statement concludes:

The death penalty is inconsistent with the fundamental right to life. There is an absence of proof that it deters crime, and it creates an unacceptable risk of executing innocent people. Rather than inventing new ways to implement capital punishment, we urge all States to put in place a moratorium on its use, as a step towards universal abolition.

Smith has been on death row since he was convicted of murder and sentenced to life without parole in 1988. He filed for an injunction on the execution, challenging the use of nitrogen hypoxia on First Amendment, Eighth Amendment, and Fourteenth Amendment constitutional grounds. However, a federal judge denied the injunction last week, allowing Alabama to proceed with Smith’s execution.

This is not the UN’s first attempt to speak out regarding the scheduled execution of Smith. Four UN experts urged US officials earlier this month to cancel the execution. Commentators from the US have similarly voiced concerns, reasoning that by executing Smith via nitrogen hypoxia, Alabama officials will violate the Eighth Amendment, which proscribes “cruel and unusual punishment.”