Lawyers for former Yukos owner Mikhail Khodorkovsky and his partner, Platon Lebedev, submitted an appeal to the Supreme Court on Friday over their December 2010 conviction on charges of embezzlement and money laundering.
A Moscow court turned down an appeal of the conviction brought by the pair last year.
In comments posted on Khodorkovsky's website, lawyer Vadim Klyuvgant reiterated the defense's position that the charges against the former oil company executives are baseless.
"The main issue that we put forth in the appeal is specifically the fact that there is in principle no basis of criminal liability," Klyuvgant said. "That is, … there are no laws in the Russian Criminal Code on the basis of which the acts attributed as criminal to Mikhail Khodorkovsky and Platon Lebedev could actually be called criminal."
Khodorkovsky and Lebedev have been in prison since 2003. They were convicted on charges of fraud and tax evasion in 2005 and sentenced to eight years' imprisonment.
New charges were brought in 2009. The pair was accused of embezzling billions of dollars worth of oil and laundering part of the profits.
They were convicted in December 2010 and are expected to remain in prison until 2016, unless the conviction is overturned.
They maintain their innocence and say the charges against them are politically motivated.