Barns was admitted to practice and called to the Victorian Bar in 1986, and to the Tasmanian Bar in 2003. He is also admitted to practice in New South Wales and Western Australia. He worked full-time as a barrister from 1986 to 1989, and from 2003. He took silk in Tasmania in May 2020. Barns represented Ezzit Raad in the 2008 trial of twelve men around Abdul Nacer Benbrika charged with terrorism-related offenses. SBS Television produced a one-hour documentary, The Trial, about the case, focussing on Barns' involvement.
Political career
Barns was an adviser to New South Wales premierNick Greiner ; Victorian opposition leaderAlan Brown ; and Tasmanian premierRay Groom. He then served as Chief of Staff to Federal Finance MinisterJohn Fahey from 1996 to 1999. Barns was the political campaign director of the Australian Republican Movement's 1999 referendum campaign and he succeeded Malcolm Turnbull as ARM chair in 2000. In 2002, Barns was disendorsed as the Liberal candidate for the Tasmanian seat of Denison, due to his criticism of the Howard government's asylum-seeker policies. Blaming John Howard, Barns said, "Dissent within the party is just not tolerated." Criticising the Liberal Party, Barns commented on, "The weakness of the liberal wing of the party and in particular supposedly liberal ministers like Robert Hill, for example, or Daryl Williams, a range of them who thought of themselves as being liberals who have been prepared to go along for the ride". He later joined the Australian Democrats for around two years. In 2013, Barns was the Wikileaks Party campaign adviser for the Australian federal election when claims were made about party lack of transparency and accountability by Leslie Cannold, resulting in her resignation from the party along with a number of National Council members and volunteers.
Writing
Barns is the author of What's Wrong with the Liberal Party? and Selling the Australian Government: Politics and Propaganda from Whitlam to Howard. More frequent contributions appear in On Line Opinion, Crikey and the HobartMercury on issues pertaining to sport, law and politics.
Human rights
In 2019, Barns told Australians to put aside their opinions of Julian Assange and consider his actions. He told the press: “At the end of the day we need to remember what is it he exposed, for which he’s been prosecuted. He revealed war crimes and he’s being punished for it.” In 2020, he called for Australians to support Assange during his extradition hearing in the UK, describing him as facing a virtual death sentence in the USA for exposing war crimes by publishing classified material on Wikileaks. Barns has made calls for Australia to adopt a Bill of Rights for the protection of its citizens and journalists. In a 2020 opinion piece published in the Mercury, he warned of the potential human rights violations that could follow public acceptance of the Australian government's COVIDSafe app. The app is intended to facilitate the contact-tracing of people who become infected with the disease, but he warns that data could be used for other purposes by other parties including police, immigration and intelligence agencies in Australia and the USA.
Law reform
In a 2012 article called "Australia's pointless and deadly drugs crackdown" he said "We are killing, injuring and hurting young Australians who use illicit drugs because of our irrational obsession with prohibition. It is time to stop and produce policies that actually work."