The solicitor-general who was forced to resign after a major falling-out with Attorney-General George Brandis has appeared before the High Court, arguing that letting MPs off the hook on the basis they did not know they were dual citizens would create chaos in Parliament.

Justin Gleeson SC is appearing on behalf of another Coalition rival, former independent MP Tony Windsor, and yesterday took aim at the case being outlined by representatives for the Deputy Prime Minister Barnaby Joyce. Appearing for Nationals Senator Matt CanavanDavid Bennett SC countered that allowing MPs to be excluded based on obscure foreign citizenship laws would only lead to a "genealogical witch hunt" at every election.