United Nations Human Rights Commissioner Navi Pillay said on Thursday welcomed U.S. President Barack Obama's decision to close the Guantanamo Bay detention center and said it was a “good day for the rule of law.” “I warmly welcome this decision,” Pillay said in a statement. “The fact that President Obama has placed such a high priority on closing Guantanamo and set in motion a system to safeguard the fundamental rights of the detainees there is extremely encouraging.” Pillay said that the controversial detention center had damaged America's reputation on the world stage. “The United States has in the past been a staunch supporter of international human rights law, and this is one of the reasons that the regime that was established in Guantanamo has been viewed as so damaging,” her statement said. “Water-boarding and other forms of interrogation that may amount to torture, detention for prolonged periods without trial or proper judicial review, and what became known as ‘extraordinary rendition.' These are all aberrations that should never have happened,” Pillay added. Meanwhile, U.N. rapporteur on torture Manfred Nowak said the news was a first sign of goodwill by the new American administration. But he warned that shutting the prison will require difficult decisions and said freed inmates should be allowed to sue the United States if they were mistreated. “Justice also means to look into the past,” Nowak told The Associated Press. Nowak has previously said he had reliable accounts to indicate that Guantanamo detainees have been tortured. Pillay called for a thorough investigation into allegations of torture at the Guantanamo center. “Under international law, there is an absolute prohibition against torture, and other cruel, inhuman and degrading treatment,” she said. “There is no let-out clause. There must be accountability for those who have ordered such practices or carried them out, and victims should receive recompense.”