Russia violated the rights of opposition politician and anti-corruption campaigner Alexei Navalny by breaking up demonstrations and detaining him on seven occasions between 2012 and 2014, the European Court of Human Rights ruled on Thursday.
Navalny, who has said he plans to run as a challenger to the Kremlin candidate in a presidential election next year, rose to prominence in 2012 as one of the leaders of the biggest protest movement of President Vladimir Putin's 17-year rule.
The protests, sparked by allegations of vote-rigging, prompted a crackdown by law enforcement.
The court in Strasbourg said the treatment of Navalny had been meant to sent a message to other Russians.
"[His] arrest and administrative detention had the effect of preventing and discouraging him and others from participating in protest rallies and actively engaging in opposition politics," the ruling said.
The court ruled that Navalny's rights to freedom of assembly and liberty had been disregarded on all seven occasions. On six of the seven occasions, his right to a fair court hearing was also violated, it said.
It ordered Russia to pay Navalny 51,025 euros ($55,184) in damages and 12,653 euros ($13,684) in costs.
Russia's Foreign Ministry did not immediately respond to a request for comment.
"This shows just how rotten and distorted the Russian law enforcement and court systems are," Navalny said in a video blog on his website in which he called on Russians to support his campaign for president and promised to clean up the justice system.
"In every case there was a judge, a prosecutor, police who detained me and wrote false reports. Tens, hundreds of people who without batting an eye committed serious offences," he said.
Navalny is currently in court facing retrial on charges of embezzlement in the regional city of Kirov, after Russia's supreme court overturned a guilty verdict last year.
A conviction could force him to abandon his hopes of competing in the 2018 presidential election. Putin has not yet said if he will be seeking re-election.