This story by Megan Gorrey is in today's Fairfax press.

A magistrate is set to decide next week whether former parliamentary speaker Peter Slipper acted dishonestly when he took several trips to Canberra region wineries at taxpayers' expense.

Commonwealth prosecutors have spent the past four days attempting to prove Slipper dishonestly used about $1000 worth of government-issued Cabcharge vouchers for trips to wineries on three occasions in 2010.

The former Queensland MP has pleaded not guilty to all three fraud charges brought against him in the ACT Magistrates Court.

Chief Magistrate Lorraine Walker reserved her decision after the hearing came to a close on Thursday afternoon.

The case had earlier stalled while a last-ditch attempt by Slipper's legal team to have the charges thrown out of court on grounds there was no defence case to answer was dismissed.

In his closing submission, counsel for the Commonwealth Director of Public Prosecutions, Lionel Robberds, QC, argued Slipper had paid for the hire car trips to wineries using multiple vouchers to make it appear the trips were for parliamentary business.

Mr Robberds said the fact Slipper asked driver Gary Green for five dockets to fill in following the first of the three winery trips indicated he wanted to cover up that the trip was personal.

''It's our submission that conversation alone is proof he was acting dishonestly,'' Mr Robberds said.

He said Slipper had filled in the dockets for the trips with false details of the destination and amounts paid, and had broken up the trips in ''quite unrealistic'' ways.

''One has to ask, why is this being done?

''It's our submission that Mr Slipper knew what he was putting into the dockets was false but he's done it anyway.

''He was acting in a personal capacity, he was having a good time on these trips, which had nothing to do with parliamentary business.''