The Australian Communications and Media Authority has told a Senate Estimates hearing that owners of websites mistakenly or maliciously added to its web filtering blacklist will have to sue it or seek redress from the Commonwealth Ombudsman -- if they can ever find out that they have been added in the first place. ACMA was responding to questions last night from Greens Senator Scott Ludlam about the revelation in March that a dentist, a boarding kennel business, a school tuckshop convenor, a site featuring Bill Henson photographs and other legitimate websites had been included on ACMA’s list of prohibited sites, leaked to the Wikileaks site. It was open to people to appeal to the Federal Court or the Commonwealth Ombudsman if they disagreed with ACMA’s additions to the list, Industry Outputs General Manager Nerida O’Loughlin told the committee. ACMA and Communications Minister Stephen Conroy were unable to respond to Ludlam’s questions about how people whose sites were mistakenly blacklisted could find out if and why they had been added, as the list is ostensibly secret and publishing it is illegal. The Minister suggested he was open to ideas about  to how to address the problem. A trial of internet filtering is currently underway with a range of small ISPs and Optus. Conroy suggested those who had leaked the ACMA blacklist had an interest in promoting child p-rnography. ACMA has only recently referred the leak to the Australian Federal Police, having spent several weeks apparently internally debating what to do about it. In the interim, ACMA has suspended the provision of updates of the list to ISPs. The answers confirm that there is no accountability mechanism in place beyond legal redress for companies and households who may be mistakenly or maliciously added to ACMA’s blacklist and no means of identifying such errors without the illegal leaking of the document. In the event of the adoption of mandatory internet filtering, as proposed by the Rudd Government, website owners -- including businesses that rely on their sites for revenue -- may find their sites are blocked without any explanation due to mistakes by the regulator. The inability of ACMA to provide a more satisfactory response is remarkable given the regulator has had two months since the list was leaked and must surely have known that it would be asked about the errors the leak revealed. ACMA’s "so sue me" approach to accountability does not provide any confidence that the administration of a mandatory filtering scheme will be transparent and fair. The vast majority of entries on the blacklist are of criminal and highly objectionable content and its dissemination is therefore inappropriate. But that makes it all the more important that ACMA’s internal processes are sound and that it has a capacity to apply a common sense test to what additions it is making to the list. The deeply-flawed online content regime, which bans online material that is no different to material legally available at the local newsagent or s-x shop, also undermines the rigour of the scheme. The Broadband Department will face further questions about internet filtering when it appears before the committee again today.