On December 15 the United Nations High Commissioner for Human Rights marked the 20th anniversary of an international death penalty treaty by calling for the universal abolition of capital punishment. Navi Pillay, the top UN human rights official, urged all states to adopt the Optional Protocol to the International Covenant on Civil and Political Rights. The protocol, which bars the death penalty, was introduced in 1989. “Abolishing the death penalty is a difficult process for many societies," she said. "[A]nd ratification of the Optional Protocol can often only come about after a period of national debate. Until they reach that point, I urge those States still employing the death penalty to place a formal moratorium on its use, with the aim of ultimately ratifying the Optional Protocol and abolishing the punishment altogether everywhere.” In her statement, she enumerated a number of issues with the death penalty, including "the fundamental nature of the right to life; the unacceptable risk of executing innocent people by mistake; the absence of proof that the death penalty serves as a deterrent; and what is, to my mind, the inappropriately vengeful character of the sentence." To date, 140 countries no longer carry out the death penalty, and 72 countries have ratified the Optional Protocol on ending the death penalty. Read the full statement below.