The U.N. torture investigator called on nations on Tuesday to end lengthy solitary confinement in prisons, saying it could cause serious mental and physical damage and amount to torture.
Solitary confinement is practiced in a majority of countries for reasons ranging from punishment to protection of prisoners from fellow inmates but is subject to widespread abuse, said Juan Mendez, U.N. special rapporteur on torture.
"It can amount to torture or cruel, inhuman and degrading treatment or punishment when used as a punishment, during pretrial detention, indefinitely or for a prolonged period, for persons with mental disabilities or juveniles," he told the U.N. General Assembly's human rights committee.
"Segregation, isolation, separation, cellular, lockdown, supermax, the hole, secure housing unit ... whatever the name, solitary confinement should be banned by states as a punishment or extortion (of information) technique," Mendez said.
Citing studies showing a significant number of people would experience serious health problems and that some lasting mental damage was caused by just a few days of isolation, he said all solitary confinement longer than 15 days should be banned.
He defined solitary confinement as an inmate being held in isolation from all except guards for at least 22 hours a day.
Mendez told reporters he conceded that short-term solitary confinement was admissible under certain circumstances, such as the protection of lesbian, gay or bisexual detainees or people who had fallen foul of prison gangs.
But he said there was "no justification for using it as a penalty, because that's an inhumane penalty."
Mendez disputed the use of solitary confinement on national security grounds, citing the case of a woman in China who was isolated for two years of an eight-year sentence imposed for supplying state secrets to foreigners.
In a written report submitted to the General Assembly, he also described as "problematic" the use of super maximum security jails where solitary confinement is routine. He cited the United States, where he said between 20,000 and 25,000 people are being held in isolation.
Referring to Bradley Manning, the U.S. soldier accused of leaking secret documents to WikiLeaks, Mendez told journalists there had been a "big improvement" in his detention since he was moved to Fort Leavenworth military base in Kansas after eight months in solitary at a military brig in Virginia.
Mendez had sought a meeting with Manning, who is awaiting a court martial, but they failed to persuade U.S. authorities to let them speak privately. Mendez said he planned to issue a report on Manning and other cases in the next few weeks.
Mendez also criticized the holding of pretrial detainees in solitary, which he said was common in Denmark. While this could be justified for short periods, it needed to be strictly controlled, he said.
Mendez, a law professor at American University in Washington, said three days he himself spent in solitary confinement under military rule in his native Argentina in the 1970s "were the three longest days in my life."