Last month the Prime Minister David Cameron announced that internet service providers (ISPs) BT, TalkTalk, Virgin and Sky had agreed to contact over 19 million existing customers to give them an "unavoidable decision" about whether to install family friendly content filters. The filters will be installed automatically for new customers of the ISPs unless the account holder, who has to be an adult, switches them off.
The scheme is to be overseen by Ofcom and is designed to offer better protection to children over the kinds of content they can view online, Cameron said.
However, BT has asked for "greater legal clarity" on the use of filters after receiving legal advice on the issue, according to a statement issued by the company.
The clarity sought is in relation to how UK surveillance laws would apply to the filtering of content, according to a report by the Financial Times.
"BT executives met with Oliver Letwin MP recently to discuss a range of policy issues," a BT spokesperson said. "During this meeting the issue of filters came up and we expressed a view that greater legal clarity would be welcome given external legal advice we have received. We have made this point several times during the past year as it is important that any plans are practical and not unintentionally derailed."
Under the Regulation of Investigatory Powers Act (RIPA), the interception of communications is generally prohibited. It is only legal to intrude on private communications if you have a warrant or both the sender and recipient of information consent to the activity, even if the interception is done unintentionally.
Telecoms firms are allowed to unintentionally intercept communications in line with RIPA if it "takes place for purposes connected with the provision or operation of that service or with the enforcement, in relation to that service, of any enactment relating to the use of postal services or telecommunications services."
It was previously the case under RIPA that, without a warrant, you only needed to prove there was 'reasonable grounds' to accept consent had been given to allow communications to be intercepted. However, those particular RIPA provisions were scrapped and updated after the European Commission launched a legal challenge arguing that the old rules did not adequately protect against intrusion into personal privacy.
The Commission's concerns were raised after it received complaints from BT customers about unannounced targeted advertising trials BT conducted through a software company, Phorm. Phorm used its technology to intercept and monitor the web activity of BT customers to help match adverts to the interests of users.
The activity prompted scrutiny by the Crown Prosecution Service (CPS) but it decided not launch a case against BT and Phorm on the basis that there was not enough evidence of wrongdoing to convict. Any breach of privacy laws could be reasonably argued was a genuine misunderstanding, the CPS said at the time. Data gathered in the trials was anonymous, not processed by people and was destroyed, according to the CPS' findings.