[PHOTO: Supreme court judges dismissed an attempt by the security forces to keep intelligence secret from those it was being used against.] Some very fine words were expressed by the supreme court judges as by majority they dismissed claims by MI5 and MI6 that any intelligence they have gathered must remain secret, withheld not only from the public but from their opponents in court. "The open justice principle is not a mere procedural rule," said Lord Dyson. "It is a fundamental common law principle." Parties have a right to know the case against them, and the right to confront their accusers, he said. "Any weakening in the face of advances in the methods and use of secret intelligence in a case such as this would be bound to lead to attempts to widen the scope for an exception to be made to the principle of open justice," warned Lord Hope.Lord Brown warned that the kind of "closed procedure" being sought "would mean that claims concerning allegations of complicity, torture and the like by UK intelligence services abroad would be heard in proceedings from which the claimants were excluded, with secret defences they could not see, secret evidence they could not challenge, and secret judgments withheld from them and from the public for all time." Under the proposals put forward by MI5 and MI6 "all the material goes before the judge and a claim that all of it involves national security or some other vital public interest will be very tempting to make", warned Lord Kerr. The immediate trigger for the case was a demand for compensation from lawyers representing British citizens or residents incarcerated at Guantánamo Bay. The prisoners, now released, lodged civil claims for damages, including for conspiracy to torture. The security and intelligence agencies denied any liability. MI5 and MI6, backed by the home and foreign secretaries, argued their case on pragmatic grounds. Some 250,000 potentially relevant documents were involved. At least 140,000 would have to be sifted, an exercise which would have taken three years to complete, they said. The security and intelligence agencies abandoned the civil proceedings and paid the former Guantánamo prisoners undisclosed but significant sums of money as compensation. But the agencies remained concerned. An earlier case, that of Binyam Mohamed, a British resident secretly flown to Guantánamo by the US and abused with British connivance, had demonstrated that senior British judges were now prepared to question claims about threats to national security and reveal intelligence information – in this case provided to UK authorities by the CIA. Judges, it seemed, were now prepared to dismiss cries of alarm from ministers and the security and intelligence establishment. Without a blanket ban on disclosure, MI5 and MI6 faced the prospect of more and more judges agreeing to disclose intelligence information. They proposed extending the use of special advocates, now used in hearings of the Special Immigration Appeals Commission (Siac), who in secret would consider evidence supplied by the security and intelligence agencies. The material would not be shown to defendants or appellants. They would not know the case against them, or see witnesses supporting claims put forward by MI5 and MI6. Special advocates would act on their behalf. Dyson warned: "In many cases, the special advocate will be hampered by not being able to take instructions from his client on the closed material." He added: "A further problem is that it may not always be possible for the judge (even with the benefit of assistance from the special advocate) to decide whether the special advocate will be hampered in this way." The supreme court judges said they objected both as a matter of principle and for pragmatic reasons to what the security and intelligence agencies were demanding. They did so in ringing terms, and immediately passed responsibility to parliament. "The right to be confronted by one's accusers is such a fundamental element of the common law right to a fair trial that the court cannot abrogate it in the exercise of its inherent power," said Dyson. He added: "Only parliament can do that." And that is just what the government now intends. It is preparing a green paper, which is expected to state that the proposals put forward by MI5 and MI6 to the courts – which they rejected – must now be incorporated in a new statute. The supreme court has passed the baton to MPs and peers. They must now be alerted to the dangers ahead. guardian.co.uk © Guardian News and Media Limited 2011