By Kelly Fiveash

The UK's Snoopers' Charter has been billed as one of the most intrusive of its kind anywhere in the Western world. But it's the proposal for a super-spy search engine – euphemistically named the 'request filter' – that is most pernicious. It's also the element that's hardest to track. EU law appears to have delayed implementation – but there are signs that it is coming back to life.

The filter has been described by critics as a Google-like distributed database, allowing government agencies to search for and organise information on citizens' web browsing habits – with the relevant data being held by telecoms and postal operators for 12 months.

The Home Office has prickled at any suggestion that it be characterised as a database, even though it admits the system would "speed up complex enquiries" – which is typically the kind of work carried out on a database.

Officials were pushing ahead with this system until something got in their way: a European legal problem.

In 2015, Labour's Tom Watson and (ironically, given his current Brexit role) then-Tory backbencher David Davis used European law to bring a successful challenge against the Data Retention and Investigatory Powers Act (Dripa), a temporary piece of emergency legislation rushed through parliament in 2014, after the EU's Data Retention Directive was found to be invalid.

The same controversial and sweeping powers on data retention were added to the Investigatory Powers Act (AKA the Snoopers' Charter), which passed into law late last year a matter of weeks before Dripa – which at the insistence of the Liberal Democrats had a built-in self-distruct date of 31 December, 2016 – was set to expire.

But the Court of Justice of the European Union ruled last December that the UK's "general and indiscriminate" retention of citizens' data communications was unlawful where it wasn't being scooped up for serious crime cases. The timing was bad news for Theresa May, who had steered the Snoopers' Charter through parliament after a number of failed attempts during her time as home secretary.

Last week, the government went into damage-limitation mode. It rowed-back on plans to give senior cops the power to authorise access to the phone and web browsing records of British citizens.

The Home Office has now opened public consultation in which it lays out – in big red pen – the changes it believes need to be made to the Snoopers' Charter in order, it believes, to comply with the ruling.

Under the proposed government amendments, an independent body at the Investigatory Powers Commission will be brought in to authorise communications data requests. It will no longer allow central and local government agencies to gather and retain data for the purpose of public health, tax collection and financial markets regulation. And a threshold has been set to restrict the use of communications data to investigations into serious crime where adults face minimum prison sentences of six months.

A recent heavily-delayed response from the Home Office to a freedom of information request revealed that, to date, no work has been carried out on the search engine.

"No work is currently underway to design a request filter," the Home Office said. "Early concept demonstrators were developed to show the policy intent to the parliamentary joint committee.” A pilot phase for the search engine was yet to be "planned or set up", it said. Nothing was in place for "any filtering arrangements for the acquisition of communications data" and "no suppliers have been contracted to develop the request filter". 

But the Home Office hasn't caved in completely. It insists that national security is "outside of the scope of EU law". Operatives at MI5, MI6 and GCHQ will continue to acquire and retain communications data, it said, including "internet connection records" such as web browsing habits. This suggests there are still plans to pursue the filter.

There is a proposed timeline for implementation. The Home Office says "filtering arrangements will not become an operational capability until after Part Three of IPA [Investigatory Powers Act] has been commenced and a code of practice has been approved by parliament".

Those draft codes – much delayed – have now been published. They cover, in detail, how the request filter will operate, with the Home Office confirming that "the service will be provided by one or more third parties under contract".

The government simply will not let plans for the filter lie. They have been set back, but the signs are that they will try to get the search engine up and running as soon as possible. The European legal ruling merely delayed it.

Kelly Fiveash is a technology journalist. You can follow her on Twitter here.

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