The Investigatory Powers Tribunal has held that general warrants cannot be used by the intelligence services to bulk surveil in a manner unless the purpose for the warrant is so specific as to be objectively ascertainable.

In the High Court on January 8 judgement was entered for the claimants responding to the question:

“Does section 5 of [the 1994 Intelligence Services Act] permit the issue of a ‘thematic’ computer hacking warrant authorising acts in respect of an entire class of people or an entire class of such acts?”

The Court found it did not.

In citing 250 year of caselaw the Court considered common law principles had well established an aversion to general warrants. They are simply to broad in scope, being able to apply to whoever or whatever the warrant searcher wishes accordingly:

“ It follows that a general warrant gives rise to an unlawful delegation of authority by the legally entrusted decision-maker to the executing official. This unlawful delegation breaches a fundamental right.“

at p.30

It was up to the Secretary of State in this instance to decide the legality, proportionality and necessity of the application for a warrant and limit it in scope in so far as was absolutely necessary. Giving such discretion to an executing official in this case would be unlawful.

Further the Court stated plainly that the common law was strongly averse to statutory construction permitting such warrants to be lawful.

It went on to state:

“The aversion to general warrants is one of the basic principles on which the law of the United Kingdom is founded. As such, it may not be overridden by statute unless the wording of the statute makes clear that Parliament intended to do so“

at p.48

The Court then went on to provide further guidance as to what could or not be achieved by a warrant:

“ A warrant in respect of “any device used at the Acacia Avenue Internet Café during the period of six months from the date of issue of the warrant” would in our view be sufficiently specific, as would “anyone who appears on the FCDO Ruritanian diplomatic list during the period of six months from the date of the warrant”.”

at p.52

As for the impermissible broad brush approach:

“the mobile phone of any person conspiring to commit acts of terrorism”) would be insufficiently specific to satisfy the requirements of section 5(2). 

at p.53

The case represents a significant step in providing greater clarity around the restrictions on surveillance tools and the interpretation of legislation in light of the common law concerning general warrants.

A step towards safeguarding privacy, certainly, in the curtailment of investigatory powers in the bulk interception of communications. It also acts as a reinforcement of the checks and balances role of the Secretary of State in approving such tools to be used.

The Privacy International press release following the judgement can be found here.