An anonymous reader writes "UK ISPs have responded to culture minister Ed Vaisey's comments regarding pervasive, opt-out only porn filtering, bringing up many of the technical and civil-liberties issues also raised on Slashdot. In response to the government proposal, Nicholas Lansman, secretary general of the Ispa industry body, said: 'Ispa firmly believes that controls on children's access to the internet should be managed by parents and carers with the tools ISPs provide, rather than being imposed top-down.' Trefor Davies, chief technology officer at ISP Timico, commented that 'Unfortunately, it's technically not possible to completely block this stuff. You end up with a system that's either hugely expensive and a losing battle because there are millions of these sites or it's just not effective. The cost of putting these systems in place outweigh the benefits, to my mind.' Mr. Davies also feared that any wide-scale attempt to police pornographic content would soon be expanded to include pirated pop songs, films and TV shows. 'If we take this step it will not take very long to end up with an internet that's a walled garden of sites the governments is happy for you to see,' he said."