Beijing: 'Without this stamp, I can't practice law," Jiang Tianyong says as he pulls a leathery booklet out of his shirt pocket. He points to a dog-eared page near the back of the book: A red imprint there grants him permission to practice law in China until May 31. The following page, where his renewal stamp should be, is blank. In a few days he'll be disbarred.

Mr. Jiang is one of at least a dozen prominent human-rights lawyers across China on the verge of disbarment in what appears to be a clampdown on their practice. Chinese lawyers must renew their credentials every year in May at their local judicial bureau or lawyers association through a perfunctory process known as the "annual exam." There is no actual test involved -- the association or bureau simply summons lawyers to its offices, confirms they have paid their dues and gives them a stamp.

But it doesn't always work this way. Mr. Jiang's story is a case in point: A former school teacher from Henan province, last year he led a group of lawyers who volunteered to represent Tibetans after the March 14 riots. That April, the Judicial Bureau sent his firm a warning letter; then the head of his firm asked him to stop taking sensitive cases and giving interviews to foreign media. He acceded to neither request and the Judicial Bureau refused to renew his license until the end of June, leaving him unable to practice for a month. This year he has continued to handle high-profile cases involving Tibetan monks, one of whom was released a few weeks ago as a result of work by Mr. Jiang and his partner. He doesn't expect his license to be renewed before it expires Sunday.

Last year Mr. Jiang was one of at least three rights lawyers known to have temporarily lost their licenses in this way, but this year there may be many more. I spoke by telephone or in person to 16 human-rights lawyers who have yet to renew their licenses. Some may receive their licenses before the May 31 deadline or shortly afterwards. But none of them will miss the official warning signal.

"Other lawyers and law firms have all been approved," says lawyer Li Fangping, who recently handled a Tibetan case with Mr. Jiang. "It is only firms and lawyers who take human-rights cases who will have to stop [practicing]."

When asked about this trend, an official at the Beijing Judicial Bureau pointed out that the deadline for license renewal is still some days away. "All lawyers are treated equally," said Dong Chunjiang, a deputy director at the Judicial Bureau. He disputed the premise that some lawyers were "rights lawyers," saying: "Our 19,000 lawyers are all protecting people's rights."

Some lawyers disagree that the government is treating them equally. They believe the license delay is linked to the sensitivity of the anniversaries of the June 4 Tiananmen crackdown and the founding of the People's Republic, as well as a general tightening of control. "The Ministry of Justice uses the 'annual exam' to limit and restrict lawyers' professional rights," says Xie Yanyi, who handles cases for people with AIDS and represents farmers in land-rights cases.

The last few months have also seen an uptick in physical violence and detentions of these lawyers. In April, two were badly beaten by thugs in separate incidents. Earlier this month, lawyers Zhang Kai and Li Chunfu were beaten up and detained while investigating a case in Chongqing.

For lawyers who lose their licenses, there is little recourse. Although technically they are allowed to sue the Ministry of Justice for reinstatement, there have been no successful cases of this nature in the past.

The lawyers who face suspension as of Sunday have handled a variety of cases, from representing parents whose children died in flimsy school buildings during the Sichuan earthquake to helping victims of the toxic milk-powder scandal sue for compensation. What these cases have in common is that they show what a powerful ally the law can be for China's underdogs.

While those cases may have sealed their fates as far as license renewal is concerned, many human-rights lawyers in China say they are working toward the same goals advocated by their political leaders. "People like us want to use our professional knowledge to help society develop a legally based system," says Mr. Jiang. "Also, I personally want to live in a society that is ruled by the law."