James Ashby, who worked as a media adviser to the Speaker of the Federal Parliament, Peter Slipper, worked to undermine his boss by giving information to a tabloid journalist and to his political rivals, a court has heard.

David Chin, the barrister for Mr Slipper, told the Federal Court today that Mr Ashby's lawsuit for sexual harassment has been designed to cause "political and reputational damage" to the Speaker and for the "political advantage of his political opponents in the Liberal-National party", including former Howard cabinet minister Mal Brough.

Julian Burnside, QC, for the Commonwealth, told Justice Steven Rares that mobile phone records show Mr Ashby and another adviser, Karen Doane, "were working together to undermine Mr Slipper when they were still working for him".

Mr Burnside alleged the two advisers "provided sensitive material" to News Ltd journalist Steve Lewis - who was present in the court's public gallery today - and provided "politically sensitive information" to Mr Brough.