Last year Hollywood's Motion Picture Association (MPA) went to court seeking an injunction against UK ISP BT in order to force them to block Newzbin2, the resurrected version of the original Newzbin Usenet indexer. This week the MPA are back at the High Court again as they attempt to force BT to use their child abuse filter to block Newzbin2.

In March 2010, the MPA won a significant legal battle against Usenet indexing site Newzbin and in May the site collapsed under a mountain of debt.

The celebrations following the site’s demise were to be short-lived. Newzbin was quickly resurrected under new management as Newzbin2, and the MPA faced the prospect of taking on new legal action against the site’s new owners. Rather than tackle Newzbin2 head on, Hollywood tried a different approach.

During September 2010, TorrentFreak learned that the MPA were developing plans to take leading UK ISP BT to court and by December we had solid proof that was indeed the case. The MPA went to court seeking an injunction against BT in order to force them to block Newzbin2.

“In launching this case, the MPA is aiming to secure an order that will enable BT to block Internet access to the site, thus preventing the site from using the Internet to make money through infringement,” the MPA informed us in a statement.

This week the MPA are back at the High Court again, hoping it can get an injunction to force BT to block the site for its 5.6 million subscribers. According to an MPA spokesperson, BT was selected for two reasons.

“BT was chosen because it’s the largest [ISP] and already has the technology in place, through its Cleanfeed system, to block the site,” she said.

Developed by BT at an estimated cost of £500,000, Cleanfeed is a content blocking system that has been operational since 2004. In conjunction with information supplied by the Internet Watch Foundation, it is used by BT to block child pornography sites.

Traffic destined for a blacklisted URL or IP address is intercepted by Cleanfeed. At this point BT impersonates the destination web server and returns an HTTP 404 status code, causing a subscriber’s web browser to show a site “not found” message.

It is unclear how much development work has been done on the system since its inception, but early versions of Cleanfeed had a number of limitations. The product only worked on the standard port for regular browsing, port 80. It was also unable to block encrypted or proxied web traffic, unless the proxy itself was on the blacklist.

Interestingly, according to comments made in 2004 by Mike Galvin, then Director of Internet Services for BT Retail, the company already had concerns that outsiders would attempt to widen the purpose of Cleanfeed. Another ISP, Wanadoo, was apparently approached by the BPI to use a system similar to Cleanfeed to block music piracy.

In response, Galvin said that if the pressure to “extend the scope” of Cleanfeed became too great, BT would cancel the project. BT has made no recent public comment to that effect in connection with this current action by the MPA.

“The MPA application to engage in censorship of the Internet for their own petty interests would, if granted, set a dangerous precedent in a Western democracy,” Newzbin told TorrentFreak in an earlier statement.

“‘Drive-by’ litigation such as this will cut off access to substantial legitimate content and is entirely unwarranted & disproportionate.”

Newzbin have already taken steps to mitigate any site blocking measures by using the TOR anonymity system.

“The MPA’s lame attempt at censoring us in the UK won’t be permitted to cut Brits off from us if it happens,” concludes Newzbin’s Mr White.