The Parliamentary Assembly of the Council of Europe (PACE), the continent’s human rights watchdog, is expected to conduct an in-depth investigation into political prisoners in Russia after passing a resolution to define what constitutes a political prisoner.

Despite heavy lobbying from Russia, Azerbaijan, Turkey and Ukraine PACE voted, at its regular plenary session in Strasbourg, to adopt a definition crafted by legal experts that clearly establishes the criteria for assessing whether an inmate can be deemed a political prisoner.

PACE, which comprises members of the national parliaments of the 47 member states of the Council of Europe, defeated an amendment that would have given the sole power of assessing political prisoner status to the European Court of Human Rights. The amendment was supported by United Russia delegates to PACE.

The definition, set out in a resolution authored by German Social Democrat Christoph Strässer, gives more teeth to PACE to investigate politically-motivated imprisonment in Russia, including the cases of Mikhail Khodorkovsky and Platon Lebedev.

PACE’s legal affairs and human rights committee has already indicated that it will use the clarification provided by the definition to scrutinise Russia and the handful of other Council of Europe member states that incarcerate people for their political beliefs and actions.

The text’s adoption marks a major victory for human rights groups in Russia that have long called for PACE to be given more powers to investigate and sanction countries that hold political prisoners.

The resolution followed an earlier debate on the monitoring of Russian human rights and legal abuses, during which its co-author described Mikhail Khodorkovsky as, “a typical political prisoner.”