From the United Nations Office of the High Commissioner for Human Rights:
The suffering of Clayton Lockett during his execution in Oklahoma on Tuesday 29th April, may amount to cruel, inhuman and degrading treatment according to international human rights law. It also appears to run counter to the 8 th Amendment of the United States Constitution, which states that “…nor cruel and unusual punishment [shall be] inflicted.” We note that the execution of a second man in Oklahoma, scheduled later on Tuesday, was stayed by the Governor, who has ordered a review of execution procedures and protocols.
The prolonged death of Clayton Lockett is the second case of apparent extreme suffering caused by malfunctioning lethal injections reported in 2014 in the United States. The other case was that of Dennis McGuire, executed by the State of Ohio on 16 January 2014 with an allegedly untested combination of drugs.
The UN Human Rights Committee and the Committee against Torture have both previously called on the United States to review its execution methods in order to prevent severe pain and suffering. Most recently, in March 2014, the Human Rights Committee recommended the US ensure that lethal drugs used for executions originate from legal, regulated sources, and are approved by the US Food and Drug Administration (FDA).
The apparent cruelty involved in these recent executions simply reinforces the argument that authorities across the United States should impose an immediate moratorium on the use of the death penalty and work for abolition of this cruel and inhuman practice. Thirty-two out of 50 states in the US still have the death penalty in their laws (in addition to the US government and the US military). Eighteen states in the US have abolished the death penalty, most recently Maryland in 2013 and Connecticut in 2012.
The UN opposes the use of the death penalty in all circumstances.
Bolding is mine.