Moscow's Basman District Court has prolonged the pretrial detention of an aide to an opposition lawmaker until October 21.
Leonid Razvozzhayev, along with the coordinator of the opposition Left Front movement, Sergei Udaltsov, was charged with preparation and organization of a mass antigovernment protest on Moscow's Bolotnaya Square in May 2012.
Investigators say the protest was orchestrated by a Georgian politician.
Razvozzhayev, who denies the charge, was ordered to leave the courtroom on September 30 after he argued loudly with the judge.
Further prolongation of Razvozzhayev's pretrial arrest can now be decided only by the Moscow City Court, as October 21 will mark one year since his arrest.
Two participants in the Bolotnaya protest have pleaded guilty and made a deal with investigators. The trial of 12 other participants is under way.
Based on reporting by ITAR-TASS and Interfax