The Australian Government is facing a legal challenge to its decision to revoke the six-month visitors visa of Scott Parkin [3], an environmental and peace activist from the Houston Global Awareness Collective. On Saturday Parkin was arrested, six weeks after he arrived in the country, on "character grounds [4]" and imprisoned pending deportation. Government officials have refused to explain the basis for re-assessing his status. Australian Greens Senator Bob Brown suspects [5] Parkin was arrested because of his campaigning against the military contractor Halliburton [6]. Two weeks ago Parkin spoke [7] at a protest outside the Sydney office of KBR, a Halliburton subsidiary. A barrister representing Parkin, Julian Burnside, has indicated [8] he will lodge an appeal against his re-classification with the Migration Review Tribunal. "If all Mr Parkin has done to be assessed a security risk is to peacefully protest [9] his opinions, then we are in serious trouble [10]," Burnside said.