Mbowe has been detained since his arrest in July, along with other senior officials of the Chadema party, just hours before they were to hold a public forum to demand constitutional reforms.
The party says the case is politically motivated, describing it as a throwback to the increasingly authoritarian rule of the late President John Magufuli.
Mbowe’s lawyer argued that the division of the High Court, known as the Corruption and Economic Crimes Division, did not have the power to hear the case.
