"Circumstances may arise in which material held by the prosecution and rending to undermine the prosecution or assist the defence cannot be disclosed to the defence, fully or even at all, without the risk of serious prejudice to an important public interest. The public interest most regularly engaged is that in the effective investigation and prosecution of serious crime, which may involve resort to informers and undercover agents, or the use of scientific or operational techniques (such as surveillance) which cannot be disclosed without exposing individuals to the risk of personal injury or jeopardising the success of future operations. In such circumstances some derogation from the golden rule of full disclosure may be justified but such derogation must always be the minimum derogation necessary to protect the public interest in question and must never imperil the overall fairness of the trial."
"The only exception to such a rule would be upon a criminal trial, when the judge if he saw that the strict enforcement of the rule would be likely to cause a miscarriage of justice, might relax it infavorem innocentiae; if he did not do so, there would be a risk of innocent people being convicted."
"We prefer to say that the outcome and instances given [in Marks v Beyfus and Ex Parte Osman] results from performing the balancing exercises not from dispensing with it. If the disputed material may prove the defendant's innocence or avoid a miscarriage of justice then the balance comes down resoundingly in favour of disclosing it."
"You will be known as. . . and will use this name in any contact with your handlers. This includes any subsequent documents that you are required to sign Your identity will be protected. You in turn must not reveal your role to anybody without first discussing it with your handlers; this includes other officers, family or friends"
"Confidentiality is not a separate head of privilege, but it may be a very material consideration to bear in mind when privilege is claimed on the ground of public interest. What the court has to do is to weigh on the one hand the considerations which suggest that it is in the public interest that the documents in question should be disclosed and on the other hand those which suggest that it is in the public interest that they should not be disclosed and to balance one against the other."
"I have considered whether a PII application could legitimately be made to withhold this sensitive information but I take the view (and lead counsel agrees) that the assistance that this information would offer to [the defence] would mean that the judge could not in all good conscience order this information be withheld whilst at the same time allowing [the defendant] to have a fair trial."
"not given in a confidential context and there was an expectation that under certain circumstances the giving of that information might be disclosed. This does not mean that, although [WV] is in a different position from a registered informant, the police are under a duty to safeguard WV's Article 2 and Article 3 rights and each state must take appropriate steps to safeguard lives within their jurisdiction. Osman v UK . . . . Regardless that WV was not a registered CHIS, the Crown Prosecution Service is mindful of the heavy responsibility that the police bear to take reasonable measures for the safety of people providing information (P C Donnelly the Chief Constable of Lincolnshire). In this case, however, this must be balanced against the public interests as regards the prosecution of a serious crime."
"Thus, even if the prosecution do not invoke the rule, the judge is nonetheless obliged to apply it."