Barnaby Joyce's political nemesis, ex-MP Tony Windsor, has hired the former government lawyer who spectacularly fell out with Attorney-General George Brandis to fight the Deputy Prime Minister in the High Court.

It is expected Justin Gleeson SC will appear in the High Court next month acting for Mr Windsor, who is party to the proceedings because he was the runner-up for Mr Joyce's seat of New England at the 2016 election.

Justin Gleeson SC, while solicitor-general, appearing at a public hearing in Parliament House. Credit:Alex Ellinghausen

Mr Gleeson will do battle with his successor as solicitor-general, Stephen Donaghue, who is representing the Commonwealth in its defence of Mr Joyce and government MPs Matt Canavan and Fiona Nash – and by extension senator Nick Xenophon.

Fairfax Media understands Mr Gleeson will share barrister duties with Ron Merkel QC, who is assisting Mr Windsor in the case along with the Fitzroy Legal Centre. Taxpayers are footing the bill the legal defence of all the MPs caught in the citizenship net, and of Mr Windsor.