“I think there is a need for everyone to be able to talk about the monarchy openly and constructively,” Anon said. “I think society is becoming more open about this.”

The Royal Palace did not comment on Anon or on the protesters’ demands for change. Prime Minister Prayuth Chan-ocha has said the king requested that nobody be prosecuted for lèse-majesté for now.

Anon was arrested within days of his call for reform of the monarchy, though on unrelated charges linked to earlier demonstrations, fuelling the protest movement as supporters rallied at the police station before he was freed on bail.

Thousands of Thai youth rally in Bangkok, testing establishment

“We dream of a monarchy that coexists with democracy,” Anon said to cheers from a crowd of more than 10,000 people in Bangkok on Sunday, Thailand’s biggest protest in years. “We must achieve this within our generation.”

Such comments infuriate royalists.

“His action breaches good morals and degraded the honour and prestige of the profession,” said Apiwat Kantong, an adviser in the prime minister’s office who has filed legal complaints against Anon in a private capacity.

“His name should be removed from the bar registration as soon as possible,” he said. Thailand’s Lawyers Council did not comment on Apiwat’s request to take this action.

At 35, Anon is older than most of the student protesters he advises. He draws on his experience of an earlier round of protests and years of court appearances to defend government critics.

Anon grew up in a farming family in the poor, rice-growing northeastern province of Roi Et, where opposition to the Bangkok-based establishment runs deep.

His activism began in high school and he started working in human rights in 2006, the year that elected populist leader Thaksin Shinawatra was overthrown in a military coup.

Once Anon qualified as a lawyer in Bangkok, he saw his mission as defending society’s weakest.

“Many cases he took are victims of harassment who nobody knows,” said Krisadang Nutcharat, another human rights lawyer.

In 2010, Anon set up a legal practice to help those affected by bloody clashes between Thaksin’s supporters and the authorities.

After the then army chief Prayuth seized power in a 2014 coup, Anon took on cases of political activists – including those who had been charged with lèse-majesté offences against the monarchy.

“In many cases, the accused spoke truthfully but the things they said are unacceptable for society at large … The court still ruled that they are guilty,” Anon said. “This is why I became interested in the monarchy.”

The reforms Anon seeks to the monarchy include reducing the king’s constitutional powers, which were expanded after he succeeded his late father in 2016, and dropping the lèse-majesté laws.

As Anon stepped up his political activism after the 2014 coup, so the arrests began. In 2015, he was charged with organising a banned political gathering.

Including the most recent arrest, he has been charged 13 times. Of the six cases that have concluded, three were thrown out and he faced fines totalling 2,200 baht (US$70) over the others. Seven cases are pending, including some for protests in 2018 to demand fair elections.

With a passion for history and literature, some of Anon’s inspiration – and the picture on his Twitter profile – is from 1950s-era Marxist historian and activist Chit Phumisak, whose publications include The Real Face of Thai Feudalism.

In his spare time, Anon writes poetry – much of it politically inspired. One line he wrote in the aftermath of the bloodshed in 2010 reads: “With red flag raised and bravely challenging, come comrades, revolt and topple this thievish state.”