In 2002, Barns was disendorsed as the Liberal candidate for the Tasmanian seat of Denison in 2002, 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 said, "The weakness of the liberal wing of the party and in particular supposedly liberal ministers like Robert Hill, for example, or (former attorney-general) Daryl Williams, a range of them who thought of themselves as being liberals who have been prepared to go along for the ride".
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.
Author and columnist
Barns is the author of What's Wrong with the Liberal Party? (2003) and Selling the Australian Government: Politics and Propaganda from Whitlam to Howard (2005). More frequent contributions appear in On Line Opinion, Crikey and the Hobart Mercury on issues pertaining to sport, law and politics (including the Australian federal election in 2007).
Barns is a spokesperson for the Prison Action and Reform Group Inc which is an independent coalition of individuals formed in response to community concerns awakened by the deaths of five people in Tasmanian prison institutions between August 1999 and January 2000. Prison Action and Reform aims to provide a forum to advocate on behalf of a silenced group (prisoners); for the improvement of existing conditions within the Tasmanian Corrections System; and for the development of a corrections system that is appropriate for Tasmania, complies with all applicable domestic and international human rights laws and accords with world best practice and benchmarks.
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.
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."
- "Being John Howard". The Age. 21 August 2004. Retrieved 1 March 2008.
- "WikiLeaks' campaign for Senate implodes". The Sydney Morning Herald. 22 August 2013. Retrieved 22 August 2013.
- "Statement of Resignation from Wikileaks Party National Council". 21 August 2013. Retrieved 22 August 2013.
- "Benbrika and others to face more terror charges" by Karen Kissane and Peter Gregory, The Age, 17 September 2008
- The Trial, 360 Degree Films
- Greg Barns at onlineopinion.com.au
- Greg Barns at tasmanianbar.com.au
- "Libs push for more jail for rapists", ABC News (14 July 2008)