Europe’s highest court said Monday that Turkey has failed to comply with its ruling that a prominent Turkish philanthropist be immediately released from jail.

The European Court of Human Rights, based in Strasbourg, ruled in 2019 that Turkey violated Osman Kavala’s right to liberty, saying his detention and trials against him were used to silence him and in effect send a chilling message to civil society in Turkey. The judgment to immediately release him became final in May 2020.

The Council of Europe launched infringement procedures against Turkey for refusing to abide by its ruling. Monday’s ruling is the latest step in the lengthy infringement process by the Council of Europe, the continent’s foremost human rights organization, and could lead to the suspension of Turkey’s voting rights or membership in the 47-nation organization.

“Turkey urgently needs to make concrete and sustained progress in the respect of fundamental rights,” said a statement from the European Union. “Turkey’s continued refusal to implement these rulings increases the EU’s concerns regarding the Turkish judiciary’s adherence to international and European standards.”

The civil rights activist was sentenced to life in prison without parole in April after the court found him guilty of attempting to overthrow the government with the mass protests in 2013. Seven others were convicted and jailed for allegedly aiding the attempt. Kavala has maintained his innocence.

Human rights groups say Kavala, 64, was prosecuted with flimsy evidence and that the case is politically motivated. Kavala is the founder of a nonprofit organization, Anadolu Kultur, which focuses on cultural and artistic projects promoting peace and dialogue.

That verdict came after another court acquitted Kavala in February 2020. He was expected to be released from prison where he was held since October 2017 in pre-trial detention but was instead re-arrested on other charges. The European court said the new charges did not contain any substantial facts.