The ACT's Chief Magistrate Lorraine Walker has adjourned a hearing into charges against the former parliamentary speaker Peter Slipper until Tuesday morning.

Slipper is accused of misusing Cabcharge vouchers between January and June 2010, mostly to visit Canberra wineries, and trying to cover it up.

He has pleaded not guilty to three charges of dishonestly causing a risk of loss to the Commonwealth.

The alleged offences occurred before Slipper was speaker.

The amount involved is believed to be about $900.

But on Monday his lawyer Kylie Weston-Scheuber told the ACT Magistrates Court the case is an abuse of process because it violates the Bill of Rights and parliamentary privilege.

She says it may even be illegal for the court to hear the case.

Ms Weston-Scheuber says Slipper could be forced to reveal secret parliamentary business if he was to defend the charges.

She told the court that the case revolved around whether Slipper was on parliamentary business while visiting the wineries.

Ms Weston-Scheuber says for the court to decide that, it would need to hear evidence regarding Slipper's conversations and phone calls.

The case began in May, but Slipper has so far only put in one appearance, when he pleaded not guilty to the charges.

Outside the court he told journalists he would vigorously defend the charges and maintain his innocence.

He also questioned why he had been targeted, and suggested other parliamentarians who had found themselves in similar situations had been able to resolve the matter administratively.

Slipper had been trying to delay the hearing because of difficulties with retaining a barrister.

But Chief Magistrate Lorraine Walker refused his application.

Slipper has already questioned why he was charged when other MPs and senators have been dealt with differently over similar sums.

The hearing is expected to last several days, with the Commonwealth calling more than 30 witnesses.

The case has been set down for seven days.

Slipper lost his seat of Fisher on Queensland's Sunshine Coast in the last Federal election.