A court case testing the legality of UberX's ride-sharing service in Victoria has taken a dramatic turn, with the Taxi Services Commission ambushing a driver inside a courtroom on Monday.

Magistrate Julian Ayres of the Melbourne Magistrates Court has been hearing the long-running case between the Taxi Services Commission and 15 UberX drivers who were caught in a sting last August.

Uber driver Nathan Brenner, whose successful appeal effectively legalised the ride-sharing service in Victoria. Credit:Simon Schluter

The Commission sent a staff member into the courtroom during a break in proceedings to serve Nathan Brenner of Caulfield North with three additional charges. This triples the potential fine he must pay to $24,200.

Mr Brenner is a well-known Melbourne music industry identity, formerly the band manager of Split Enz and Men at Work.