Few defendants wear defiant smirks in Russian courtrooms. But for Alexei Navalny, such appearances have become almost comically commonplace.

Navalny is a Russian political activist who skyrocketed to prominence after publicizing investigations that exposed high-level government corruption. On YouTube, his videos have received more than 127 million views.

Today, Navalny is the only man tens of thousands of Russians will respond to when asked to march against the government. Most recently, scores of Russians took to the streets across the country on March 26 to protest corruption in a rare display of dissent.

Navalny, along with hundreds of others, was detained by police that day. On March 27 he was sentenced to 15 days in prison -- the latest in a string of politically-motivated sentences targeting the opposition figure.

Navalny has also been the victim of violent assaults, with the most recent seeing someone throw green dye in his face -- a common attack against Russian opposition leaders that left him mostly blind in one eye.

“This was an organized attack on Alexei Navalny by the special services of Russia, at the direction of the Kremlin,” American investor Bill Browder told CTV News from London.

Browder is widely regarded as Russian President Vladimir Putin’s most vocal foreign critic. He has received his fair share of death threats too.

Although mysterious deaths seem to be the fate of many Kremlin critics, Browder believes that Navalny is immune for now.

“If he was dead, he would become the martyr of the revolution,” Browder said. “And they understand that.”

The next anti-corruption protests are scheduled for this time in June.

Coincidentally, Putin has just signed a decree banning all rallies that are not approved by Russia’s Federal Security Service, which superseded the infamous KGB in the 1990s.

Despite the restriction, Navalny says that the protests will on as planned.

With a report from CTV National News London correspondent Daniele Hamamdjian