The trial, which has the backing and support of the Home Office, will block access for BT internet customers to any web site on a blacklist compiled by the UK Internet Watch Foundation (IWF). The IWF is an EU and industry-funded body that works with ISPs, telcos, mobile operators, software providers, police and Government to minimise the availability of illegal internet content, particularly child abuse images.
The IWF blacklist relates to worldwide child sexual abuse web sites that have been assessed as "illegal to view" in the UK.
Under the Protection of Children Act of 1978, the "taking or making" of an indecent photograph or pseudo-photograph of a child is prohibited. Making includes the situation where a person downloads an image from the internet, or otherwise creates an electronic copy of a file containing such a photograph or pseudo-photograph.
To be an offence such "making" must be a deliberate and intentional act, with knowledge that the image made was, or was likely to be, an indecent photograph or pseudo-photograph of a child.
The Sexual Offences Act 2003 made an amendment to the 1978 law by creating a defence to a charge of "making". A defence is available where a person "making" such a photograph or pseudo-photograph can prove that it was necessary to do so for the purposes of the prevention, detection or investigation of crime, or for the purposes of criminal proceedings. A person accidentally finding such an image also has a defence to that act of making.
The IWF's blacklist is collated from the reports it receives via its internet hotline and grows by more than 3,000 potentially illegal child abuse web sites every year.
Masons, the law firm behind OUT-LAW.COM, recently began acting as General Counsel for the IWF.
Tony Fagelman, General Manager of the IWF, said:
"We are extremely pleased to have the expertise and guidance of Masons and the OUT-LAW team available to us. We operate in a specialist and niche area, governed by UK legislation. This requires key knowledge and understanding and legal services and support are fundamental for our effective operation."
The system used by BT, known internally as Cleanfeed, works by blocking requests from subscribers to access the blacklisted sites, returning an error page instead. The access request will be logged by BT, but no user details will be retained, according to the telco.
Peter Robbins, CEO of IWF said:
"We believe that everyone is entitled to an abuse free online environment. Our child abuse image database contains details of websites, which if knowingly accessed by UK consumers could lead to them committing criminal offences under UK law. By preventing access to that content, BT are protecting their services and their customers."
Critics point out that it is easy for porn sites to change their web address, and thus avoid the blacklist. BT readily admits this:
"BT does not pretend that this trial will offer a total solution to this problem, or that BT alone could provide such a solution, but we believe it is an important step in the right direction."
Porn accessible through peer-to-peer networks or spam e-mail will remain unchecked.
The scheme is also provoking controversy among privacy advocates, who see Cleanfeed as the first step down the slippery slope to internet censorship – until now the province of oppressive regimes such as those in China and Zimbabwe.
"If the technology is there for one thing, it can be used for something else," Barry Hugill of civil rights group Liberty told PCPro.co.uk. "Whilst it would be invidious for us to complain about child pornography, if it was carried over to Chinese style blocking of political content we would be very concerned."
"What worries me is that this move would not only create a precedent, but an infrastructure for further expansion into censoring web sites," Simon Davies, director of Privacy International told Reuters.
But, speaking to Reuters, Pierre Danon, head of BT retail services, dismissed these fears. "In the UK, because it is illegal to view these images, we can stop an illegal activity," he said. "We do not intend to, nor can we, extend this to other areas".
In the US, the State of Pennsylvania has been trying to force its ISPs to adopt a similar scheme, but is fighting legal battles with civil liberties groups over fears that the scheme would also block access to many legitimate sites that just happen to share the same hosting company as the one blacklisted.
BT has indicated that it may be possible to extend the technology to other ISPs, if they wish to follow suit.
In response, the UK's Internet Services Providers' Association (ISPA) told The Register that in practice this would not be easy:
"Each ISP has a different infrastructure. This means that there is no 'one size fits' all technical solution to preventing access to web sites offering illegal images in territories outside of the UK. As with any technical solution, care must be taken to ensure blocking web sites offering illegal images does not cause collateral damage. Any such technical measures installed by ISPs must be evaluated over time to judge their success."