The case against former speaker Peter Slipper rests on whether he knew his actions could cause a loss to the government and that he acted dishonestly.

Whether Peter Slipper is found guilty of misusing taxpayer funds could come down to his intentions on three days more than four years ago.

The dishonesty case against the former parliamentary Speaker narrowed when he admitted paying for trips to wineries outside Canberra with commonwealth Cabcharge taxi vouchers.

His admission means the case now rests on whether he knew his actions could cause a financial loss to the government and whether he acted dishonestly.

The two drivers who escorted Slipper to various wineries gave evidence on the first day of his week-long trial at the ACT Magistrate’s Court on Monday.

Slipper is accused of misusing about $900 worth of Cabcharge vouchers and faces up to one year in prison or $10,000 in fines if convicted.

Hire car driver Gary Green told the court he drove Slipper and another male around several wineries for four-and-a-half hours on January 20, 2010.

As the day wore on he noticed Slipper was affected by alcohol and was “flushed in the face”.

“I could smell intoxicating liquor through the car,” he told the court.

Despite the trip taking place a long time ago, Mr Green remembered it because it was “unusual”.

On two other occasions in 2010 another driver, Berris Crossin, took Slipper and a male passenger to visit wineries in the same region.

On all three winery trips Slipper used multiple Cabcharge vouchers to divide the fares into smaller amounts, using descriptions like “parliament to suburbs” and “suburbs to suburbs”.

The prosecution alleges Slipper knew he was breaking the rules and that his actions could cause a financial loss to the commonwealth.

This, the prosecution argues, is why he split up the trips.

MPs and senators can only use taxpayer funds to pay for official or parliamentary business.

But Slipper’s lawyer, Kylie Weston-Scheuber, said whether the government incurred any financial loss from her client’s actions was in dispute, as were his intentions.

In June, Slipper’s legal representatives argued the charges should be dismissed under the Mental Health Act due to his state of mind.

The court was told that the former speaker had spiralled into despair as a result of criminal allegations.

In 2013, he had twice attempted to take his own life.

Chief Magistrate Lorraine Walker ruled the trial go ahead in the public interest.

Eight witnesses will take the stand during the trial and evidence from a further 27 will be submitted.

Slipper is a former Queensland Nationals and Liberal MP who later sat an Independent. He who served in parliament for two decades, but failed to retain the seat of Fisher at the 2013 election.

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