Former Ukrainian Prime Minister Yulia Tymoshenko is appealing to the European Court of Human Rights against her imprisonment by Ukraine on charges of abuse of office.
Tuesday's hearing comes a day before Ukraine's high court is expected to rule on her appeal against her conviction and seven-year sentence.
The abuse of office charges are linked to a natural gas deal she brokered with Russia in 2009 while she was serving as prime minister.
She also faces separate charges of embezzlement and tax evasion, in a trial expected to resume September 11.
Tymoshenko, a co-leader of the 2004 pro-democracy Orange Revolution, says both cases amount to a political vendetta against her by President Viktor Yanukovych, who won a narrow victory over her in 2010 voting.
Some information for this report was provided by AP, AFP and Reuters.