By Dominic Casciani
It is a major decision about the legality of using secret evidence
Three terror suspects whose freedom is restricted by control orders have won a legal battle in the House of Lords over the use of secret evidence.
Nine Law Lords unanimously ruled it was unfair individuals should be kept in ignorance of the case against them.
They did not quash the men's orders, but one warned the ruling could spell the end of the control orders system.
The home secretary called the decision "disappointing" but said all control orders would remain in force for now.
The Home Office uses control orders against terror suspects who cannot be tried because of secret intelligence.
In practical terms, the ruling means the cases must return to the High Court lower courts to be reheard.
In turn, the Home Office will need to decide either to release more material to the men and to the public - or rescind the orders.
LIVING ON A CONTROL ORDER
Where's the evidence - It's all closed material, I can't defend myself, I'm in the dark, I'm in this nightmare
Controlee AE, speaking to the BBC
Home Secretary Alan Johnson said protecting the public was his "top priority".
"This judgment makes that task harder," he said, insisting they tried to ensure reliance on sensitive material would not affect the right to a fair trial. He said the government would now consider its options - but all control orders would remain in force.
The three suspects, an Iraqi, a British man and a man who has dual Libyan/UK citizenship, have been held on control orders for between two and three years.
Under the system, terrorism suspects have their liberty restricted with home curfews, electronic tagging and bans on whom they can meet and where they can go.
The men are not allowed to see any of the secret intelligence assessments that form the basis of the restrictions, but they can still mount a legal challenge.
Ruling in favour of the men Lord Phillips of Worth Matravers, the senior Law Lord on the case, said: "A trial procedure can never be considered fair if a party to it is kept in ignorance of the case against him.
"If the wider public are to have confidence in the justice system, they need to be able to see that justice is done rather than being asked to take it on trust.
"The best way of producing a fair trial is to ensure that a party to it has the fullest information of both the allegations that are made against him and the evidence relied upon in support of those allegations."
Lord Hope of Craighead added: "The consequences of a successful terrorist attack are likely to be so appalling that there is an understandable wish to support the system that keeps those who are considered to be most dangerous out of circulation for as long as possible.
"But the slow creep of complacency must be resisted. If the rule of law is to mean anything, it is in cases such as these that the court must stand by [legal] principle. It must insist that the person affected be told what is alleged against him."
Muhammed Ayub, solicitor for one of the three men, known as AE, said: "We are pleased with the judgement, it's absolutely clear that evidence that is not disclosed cannot be relied upon."
But Lord Hoffman, one of the nine Lords, said their hands had been forced in part by an earlier European Court of Human Rights judgement.
He said: "I think that the decision
was wrong and that it may well destroy the system of control orders which is a significant part of this country's defences against terrorism."
As of March this year, 17 men were being held on control orders and there are at least another 20 deportation cases involving similar national security material.
Shadow home secretary Chris Grayling said: "This is further evidence of the government's failure to create a proper regime to control dangerous terror suspects in the UK. They have set up a system which just isn't working properly and is in urgent need of review."
And Eric Metcalfe of expert legal group Justice said the judgement supported the opinion of many senior lawyers.
"The House of Lords judgment marks a turning point. The government can decide to limp on with the use of secret evidence for the sake of ever-diminishing returns.
"Or Parliament can act to end its use once and for all. Either way, the unfairness of secret evidence is clear."