More than three weeks ago, when Huang Haibo was placed in 15 days' detention for soliciting a prostitute at a Beijing hotel, the scandal surrounding the popular television actor was hotly debated among the public, with his critics and sympathisers in about equal measure. Last week, when Beijing police decided to detain Huang for a further six months under what is called "detention and re-education for those involved in prostitution", opinion swung abruptly to overwhelming support for Huang, with an outcry against what many saw as a government abuse of human rights. Earlier, the debate was about the conduct of a man regarded as a "nice everyman", with critics saying his behaviour was immoral while sympathisers said he should not be too closely scrutinised for his actions. Now Huang's extended detention shifted attention to a far bigger controversy, with many legal experts questioning the legitimacy of a government regulation to introduce this type of detention. Many saw it as reminiscent of a darker, more repressive era. In an open letter to the Standing Committee of the National People's Congress last weekend, some 40 lawyers, legal experts and leading scholars including Jiang Ping called for the regulation to be annulled, arguing that it lacked legal foundation and jeopardised justice. Jiang is a former vice-chairman of the NPC Standing Committee's Law Committee and a former president of the China University of Political Science and Law. Early last month, a similar letter by 108 people including former legislative staff, legal professionals and women's rights activists was sent to the NPC Standing Committee. A key argument of both was that the administrative procedure for handing down detention and re-education, regulated in 1993 by a State Council regulation, violated the spirit of China's constitution and the Legislation Law. Under the Legislation Law introduced in 2000, punishment that restricts personal freedom must be regulated by law. Experts compared detention and re-education for those involved in prostitution to the recently abolished laojiao , or "re-education through labour", saying both shared similar characteristics. Under current law, an individual cannot be incarcerated without due process, such as a court procedure. However, police can assign a person to detention and re-education - for up to two years - soley by administrative means without having to go through a judicial investigation or court hearing. Last week, more than 20 lawyers at the Beijing Dacheng Law Offices sought information from the Ministry of Public Security on the country's re-education detention centres. According to earlier media reports, China has set up 200 re-education detention centres, able to hold about 300,000 people, in the past 13 years. Amnesty International estimated that 500,000 people in China were enduring punitive detention without charge or trial, and millions more cannot access the legal system to seek redress for their grievances. While the government tolerates no political dissent, it has on occasion responded positively to calls for improved human rights in non-political areas for ordinary citizens. That is why it was possible for Huang's case to be debated so publicly. And commentaries in state-run media, including one in the Procuratorial Daily (affiliated with the Supreme People's Procuratorate or state prosecutors' office) said cases like Huang's could trigger a review and eventual end of the detention and re-education system. The most significant progress in Huang's saga is that state media has, for the first time, publicly acknowledged violations of the constitution and human rights by the government over its treatment of prostitutes and their clients. cary.huang@scmp.com