It wasn’t until Li Xifeng began vomiting blood that she was given a real break.

Sent to one of China’s more than 300 labor camps with no trial or criminal charges for petitioning on behalf of her jailed husband, she said she was forced to glue pieces of plastic to the top of bottle caps — thousands of bottles a day, seven days a week, with little sleep or water and nutrition-less food. For seven months, Li, a farmer, said she worked until her body gave out and forced guards to take her to a hospital.

“You eat so much bitterness there, more than anyone should deserve,” she said of her imprisonment, which stretched from 2009 to 2010.

After decades of stonewalling, Chinese officials have begun to address public concern about the camps, slowing their use and signaling that a parliamentary meeting of China’s top leaders in Beijing this week could bring broader changes.

That prospect has thrust the camps forward as an early litmus test of how serious China’s new top leaders are in vowing to reform broken and corrupt parts of the government. But it has also invited skepticism from human rights activists and legal scholars who have long regarded China’s legal system as a source of injustice.

The obstacles to reform have also become increasingly apparent in recent weeks as government officials have backtracked from the initial idea of abolishing the labor camps, even though they operate outside the legal system.

A big hurdle, legal experts say, is that authorities have grown dependent on labor camps as an expedient way to silence critics. Police can send people to the camps for up to four years with no judicial process. Citizens have been punished for crimes as trivial as writing an unflattering blog post about a local official. Some prisoners are there because of their religious practice or because they have tried to raise complaints about local injustices to central authorities.

The camps provide what is essentially free labor to state ventures. But critics say the practice has also undermined the government’s claim to abide by rule of law.

“They know it’s bad for China’s soft power abroad and for legitimacy at home,” said Jerome Cohen, a Chinese law expert at New York University.

“Reeducation through labor” sites began under Mao Zedong in the 1950s as a way to deal with political enemies. Statistics are hard to come by, but according to the government, in 2008, 160,000 people were held in 350 such facilities throughout China. Comparisons to other countries are difficult because of China’s inconsistencies in reporting data and its common practice of detaining people who have not been charged.

Stories abound of the harsh conditions at the camps: sleep deprivation, freezing temperatures, regular beatings, barely edible food and little respite from the relentless pace of factory work.

Li, 56, was sent to a camp in Hebei province after trying to appeal her husband’s imprisonment. She said she wasn’t allowed a single shower during her seven months there. Over time, her body ached and she grew frailer.

“It’s only after I began vomiting blood and they found my condition was quite serious that they released me,” she said. “To avoid me dying in there.”

Even now, Li sometimes daydreams of the camp being consumed in a fiery explosion if only to put an end to misery of all those continuing to suffer there.

In January, China seemed poised to end all such camps when the ruling Communist Party’s top security official, Meng Jianzhu, was reported by state-run media promising to “halt” the labor-camp system once China’s parliament approves the measure at its March meeting. But in following days, official reports changed the wording of that announcement from “halt” to “reform,” suggesting Meng’s proposal had encountered internal opposition.

In the face of such ambiguity, legal experts say China’s leaders could go in myriad directions to deliver on its promise of reform — from reducing the maximum years a person can be confined to a labor camp to involving lawyers and judges.

The biggest fear among human rights experts is that the coming reforms will simply be used to add a legal veneer to the current system, further entrenching its existence.

To abolish the camps in one swift move would raise difficult questions, said Wang Gongyi, a retired researcher for the Ministry of Justice. “For instance, what do you do with the tens of thousands who are supposed to serve out their time in the camps?”

But the momentum is clearly shifting against the camps, he said, noting that internal government statistics showed the number of detainees steadily declining all last year. “Clearly the top leaders have reached a consensus about the camps, but they are still arguing about what comes next, what do you replace it with and how do you handle the consequences.”

Zhang Jie contributed to this report.