MI5 has lost control of its data storage operations and has been obtaining surveillance warrants on the basis of information it knows to be false, the high court has heard.
The security agency has been accused of “extraordinary and persistent illegality” in a legal challenge brought by the human rights organisation Liberty.
The failures have been identified by the official watchdog, the investigatory powers commissioner, Lord Justice Fulford, and admitted in outline by the home secretary, Sajid Javid.
[...]
In written submissions, Jaffey said: “Fulford’s generic warrant decision notes that warrants were issued to MI5 on a basis that MI5 knew to be incorrect and the judicial commissioners [the watchdogs] were given false information.”
There's more here, but the short version is that MI5 has never complied with the Investigatory Powers Act, and the "safeguards" the government promised when enacting it were bypassed by deceit. Which ought to be a warning to every democracy about granting powers to spies. Meanwhile, the IPC has said that until MI5 improves its data handling, applications for spy warrants will not be approved. Hopefully that will provide them with an incentive to sort their shit out.
(In NZ, sadly, the government response to this sort of issue would be to change the law to retrospectively legalise this criminal behaviour, while allowing the spies to do whatever they want).