While ISPs are private firms, they perform a public service. They have a special duty in society as providers of information not to bias that information through private censorship policies. When they embark on any form of site-blocking, ISPs cease to be doing their job. Governments should maintain that ISPs act as neutral gatekeepers of information and not take up the role of ad hoc censor. Moreover this would be different from filtering adult content as that is a service that is provided if the subscriber wishes it, if this was the case with extremist content then such a block would be useless as those interested in extremist content would just opt for packages that do not restrict access.