text: Evidence from released detainees confirmed that such practices continued and had been used against democracy movement detainees. Her organization had also reported overcrowding and harsh prison conditions. Released students had reported being locked up in cells of 12 ft. by 15 ft. with 14 to 22 other prisoners, and having to sleep on wooden planks on the floor. One student had been punished for singing in his cell; he had been manacled for 18 days, unable to stand up, use the lavatory or feed himself. Another student had reported being in prison for a year, only once being allowed to go out to an open courtyard for fresh air, for half an hour. E/CN.4/Sub.2/1990/SR.26 page 7 37. The International League had recently obtained eyewitness evidence that Chinese authorities had for some time been making unauthorized use of the organs of executed prisoners for medical transplants, without permission from the detainee or the family. That practice, freely admitted to by a number of Chinese hospitals, constituted cruel, inhuman and degrading treatment or punishment, within the meaning of the Convention against Torture, to which China was a party and under which China had undertaken to prevent such conduct within its territory. The Sub-Commission should call upon the Chinese Government to give details of the extent of the practice of using prisoners' organs for transplant, its legality under Chinese domestic law and what steps the Government proposed to take to eliminate it. 38. She also drew attention to the case of Zhang Zhenhai, a pro-democracy dissident, who had hijacked a Chinese aircraft to escape persecution and seek political asylum. The aircraft had landed in Japan on 16 December 1989, Mr. Zhang had been apprehended by Japanese authorities, his wife and son had been returned to China on the same plane with the other passengers and 
analysis: The text primarily discusses human rights violations in China, specifically related to prison conditions, treatment of political prisoners, and the use of executed prisoners' organs for medical transplants. The focus is on the violation of human dignity and the need for the Chinese government to take action to prevent such practices. This suggests that the text falls under the category of human rights and humanitarian aid.