The long-awaited hearing into the security services' bulk collection of communications data, including personal information, opened in London today.
Privacy International, the organisation behind the action, argued that successive governments had expanded their interpretation of the powers of surveillance to effectively allow MI5, MI6 and GCHQ to build vast databases of communications and internet data.
The documents provide evidence that MI5, MI6 and GCHQ collected data on every citizen in the UK, including location information, telephone numbers dialled and calls received, as well as metadata regarding time, date and duration of calls.
In addition, the security services are accused by Privacy International of bulk collecting data via the internet, including browsing history, IP addresses visited, instant messaging data and operating systems.
The bulk collection of personal information even includes physical post data.
The hearing of the Investigatory Powers Tribunal is expected to last until Friday. It heard today how the government and the secret services had exploited wide-ranging powers in the Telecommunications Act of 1984.
This was passed to smooth the privatisation of BT but also contained powers that enabled the government to make wide-ranging demands of all telecoms companies in the UK, not just BT.
The little-debated Article 94 of the Act gave the security services wide-ranging powers of surveillance, eavesdropping and bulk data collection, allowing them to operate in secret with few safeguards and little oversight. It could also, in theory, have allowed the security services to conduct their own eavesdropping direct on telecoms operators' networks.
Furthermore, the "expansionary interpretative powers" of surveillance and bulk data collection under the Act were able to continue unchecked, according to Thomas de la Mare QC of Blackstone Chambers in his opening arguments for Privacy International in court today.
De la Mare said that these already wide ranging powers were unlawfully expanded owing to a lack of proper oversight.
Dr Julian Huppert, the former Liberal Democrat MP for Cambridge who campaigned against state surveillance during his five years in office, and is now a lecturer at the University of Cambridge, talked to V3 today in a break in proceedings.
"The Telecommunications Act of 1984 was the legislation that privatised BT. Tucked in right at the end was the notorious Section 94, an incredibly broad power that essentially allows any secretary of state to require any telecommunications company to do, basically, anything. Directions of a general character," he said.
"It's incredibly powerful and has never really been debated in Parliament. There's only one mention that I can find in any of the discussions in which the Bill was specifically discussed."
It's such powerful legislation that it has to be declared to Parliament every time it is used, unless it's in the interests of national security or relations with another country.
This means that, while Parliament has never been informed of its use until recently, Section 94 was broadly used to justify an increasing range of intrusive and wide-ranging surveillance activity by the security services.
Intel claims 'world first' in artificial intelligence that can be plugged-in almost anywhere
Trusts have purchased almost 385,000 new PCs since 2013, at a cost of £260 million
The council will use funds from the project to fund network expansion
Mark Vartanyan was working for Norwegian e-healthcare firm Dignio when he was arrested