Civil rights protesters in China are being dumped in psychiatric wards where they are forced to take mind-altering drugs and given electric shocks.
The treatment is handed out to petitioners - victims of corrupt local governments who have come to the cities to seek justice.
They travel thousands of miles to reach Beijing, but instead of being allowed to voice their grievances they are thrown into illegal "black jails" and many end up placed in mental institutions.
"Pain? You don't know pain until you have had 220 volts going through your body," said Hu Guohong, who had come to Beijing to seek compensation for three months' back pay.
He suffered two hours of electric shock for ten consecutive days.
"My whole insides… it felt like my intestines were turning like clothes put through a washing machine," he said.
"There are a lot of people who are locked up there. Just like me, protesters. They round you up and simply dump you in the hospital. If you don't do what they say, you get electrocuted."
Sky News gained access to one of the mental institutions and spoke to those behind the bars of an exercise courtyard.
"Some people in here are not even diagnosed with a mental illness. There are all kinds of cases, but most of us are not ill," one man told us.
Liu Feiyue is a lawyer representing hundreds of those detained.
His home in Wuhan in South China is under surveillance by police and we had to meet secretly late at night.
He says the practice of putting protesters in mental hospitals is widespread.
"They want to stop the protesters from voicing their dissenting views," he said.
"So they lock them up in mental hospitals. This is becoming a serious epidemic in China."
Sky News wrote to the Ministry of Justice and the Ministry of Health to ask why mental hospitals were being used as dumping grounds for those seeking justice.
We received no answer.
A spokesman at the Chinese Embassy in London said it was "not in a position to respond in this regard".