Shenzhen - When local officials warned striking shoe factory workers in China's Pearl River Delta this summer that they were breaking the law, a slight, bespectacled figure barely 1.65 metres tall faced them down.
"Where is the law that says striking is illegal? If this activity is prohibited by the law, then you need to say so with crystal clarity. Which law is it?" labour lawyer Duan Yi said he told them, with his characteristic growl.
They had no answer.
While striking workers and those helping them have often been harassed, detained and sometimes imprisoned, Duan, 57, is unscathed after nearly 10 years spent testing the boundaries as China's economy has been transformed.
"If you industrialise," says Duan, "it inevitably touches upon industrial relations. And if you don't resolve the problem of labour-capital relations, your industrialisation won't go very far."
China's ruling Communist Party is deeply paranoid about social instability arising from labour disputes. Though the country boasts the biggest union in the world, the All-China Federation of Trade Unions (ACFTU), it is a state-run body that critics say regularly favours investors over workers.
Under President Xi Jinping, pressure has intensified on rights advocates, but that has not stemmed a wave of labour activism engendered by a slowing economy, shifting demographics and the rise of social media.
The rope that Beijing appears to give Duan is, say some, a recognition in official circles that labour disputes have not always been well handled.
Even President Xi, behind closed doors, criticised the ACFTU in late 2013 for not doing more for workers, according to academics and former union cadres.
"We hear internally that (Duan) has support," said a scholar at a state-run training institute linked to the ACFTU, the only legal union.
"The fact that there is space for him to exist shows that there are certain forces that have given him that space."
It helps that Duan, a dynamo in golf shirt and slacks, has a pedigree. The son of a military officer and a government ministry worker, he spent his childhood among "princelings" in an army compound in Beijing.
The hint of swagger in his walk might reflect that past or his eminent present.
"He is the concertmaster of China's labour movement," said Beijing-based scholar Wang Jiangsong.