Innocent commuters are being bullied into paying myki fines by the state's transport department in an apparent "standover racket", human rights lawyer Julian Burnside QC says.

Mr Burnside, one of Australia's most formidable barristers, has taken on a ticket infringement case pro bono amid allegations the department was avoiding legal scrutiny of the $1.5 billion fault-plagued ticketing technology.

But just days before he could challenge the fine in court, and hours after it was contacted by Fairfax Media, the department withdrew the charge against his client.

"If they had confidence that the system operates properly then they wouldn't be withdrawing the charges in circumstances such as this," Mr Burnside said. "It's nothing but a standover racket, if people are being bluffed into paying up when they could defend it because they haven't committed the offence."