Investigatory Powers Tribunal dismissed secret services' bulk data collection following lobbying by MI5

"Improper" agreement meant IPT was unable to properly fulfill

The judges at the Investigatory Powers Tribunal failed to hold the secret services to account after a secret briefing with MI5 in 2007 persuaded them that they did not have to disclose the bulk personal datasets of information that they held on citizens to the Tribunal, according to a document disclosed today by pressure group Privacy International.

The decision meant that, as complaints were brought to it, the Tribunal would not get to see the full extent of information MI5 held about people in bulk personal datasets. The Tribunal was therefore unable to carry out its work effectively and failed in its duty to provide oversight for the secret services' data-collection activities.

The Tribunal is the only check on the power of the home secretary and secret services preventing them from engaging in mass surveillance of citizens. Privacy International claims that the secret services were enabled by a little-debated section in the 1984 Telecommunications Act privatising BT to build-up vast bulk datasets of personal information about UK citizens.

Caroline Wilson Palow, general counsel for Privacy International, described the meeting and the decision arising from it as "improper".

The Tribunal, she added, "needs to maintain the neutrality and respect that would be expected of any court or tribunal. A fundamental requirement of any court is to treat each party as fairly and neutrally as possible. What this document shows is possible a failure of that neutrality".

She added: "Even more troubling, the IPT was asked to agree that it would refrain from carrying out part of its job of investigating whether MI5 unlawfully held any material about a particular claimant. Instead, MI5 requested that a vast chunk of the information it holds about all of us be off limits to future claimants."

The claims were made during a hearing this week brought by Privacy International - and brought before the Tribunal, which was overseen by judges who had not been present at the meeting in 2007.

The Tribunal will finish on Friday after hearing evidence for four days.