When Chinese legislators recommended the abolition of “education” detention centres where prostitutes and clients can be held without charge for two years, activists hoped the facilities’ days were numbered.

But they will have to wait longer.

The rubber-stamp National People’s Congress (NPC) passed only one new law when it ended its annual session on Friday – and it had to do with opening up foreign investment.

Under the nearly three-decade-old system, police have unilateral power to detain sex workers and their clients for up to two years in “shelter and education” centres.

Critics say the centres have little to do with education.

“There may be resistance inside the regime against abolition, perhaps by the police, as this would take away some of its arbitrary detention powers,” said Wang Yaqiu, a researcher at Human Rights Watch.

In 2013, testimonies of ex-detainees collected by Asia Catalyst – an organisation that defends the health of marginalised groups in the region – revealed the harsh living conditions in the centres.

These included ill-treatment, forced labour, and the obligation to pay for subsistence and forced medical examinations at prohibitive prices.

“All this is a matter of money, the talk of rehabilitation or ideological education is hollow, it is just a way of extorting money on behalf of the state and the police”, one of the women told the group.

Shen Chunyao, chairman of the NPC Standing Committee’s legislative affairs commission, said in December that “the time has come to begin the work of abolition”.

“In recent years, the use of the detention and education system has gradually decreased, the number of people in the centres has clearly diminished and they have been banned in some places,” he added.

Discussion over the future of the centres came after China’s top legislative committee abolished its system of “re-education through labour camps”, known as “laojiao”, in 2013.

Shutting the labour camps – introduced more than half a century ago as a speedy way to handle petty offenders – closed the curtain on a dark aspect of the country’s modern history long criticised by human rights groups and which Chinese officials admitted was no longer viable.