The European Court of Human Rights has ruled that Russian authorities violated the rights of an activist who was jailed for his participation in a massive antigovernment protest in Moscow in 2012.

The January 5 ruling by the Strasbourg court was a pointed rebuke to Moscow just weeks after President Vladimir Putin signed into law measures that allow Russia to reject decisions by international courts.

Yevgeny Frumkin was detained by police on May 6, 2012, on the eve of Putin’s inauguration for his third term, along with hundreds of others who had participated in a protest at Moscow’s central Bolotnaya Square.

Thousands joined the demonstration, which ended with protesters clashing with police. It was one of a series of protests in 2011-12 that were the largest since Putin first came to the presidency in 2000.

In its ruling, the Strasbourg court, known as the ECHR, said Frumkin spent a night in custody without being charged and the court refused to explain to him the reasons behind his arrest. The court said the authorities also violated Frumkin's right to peaceful assembly.

He was sentenced to 15 days in detention for failing to obey police orders.

The court also ordered Russia to pay a total of 32,000 euros ($34,400) in compensation and to cover court expenses.

“In my view, [this verdict] acknowledges once again the most important fact that there is no justice in Russia,” Frumkin said in a televised interview. “It is because [defendants] are not being given a chance to defend themselves in court and there is no objective and independent court as such.”

Several dozen people have been prosecuted in connection with the 2012 demonstration.

In 2013, the ECHR ordered Moscow to pay nearly 2 billion euros ($2.2 billion) to shareholders of Yukos, an oil company that was once Russia’s largest until it was broken up and many of its assets absorbed by state-run companies, such as Rosneft.

On December 14, Putin signed a law that gave Russia’s Constitutional Court the power to decide whether to enforce verdicts by interstate courts like the ECHR.

The new law was widely seen as a response to the ECHR’s Yukos ruling, though Russian legal scholars questioned its legality, saying it contradicted Russia's own constitution.

Russia at one point had more cases being heard before the ECHR than any other member nation.