Lord Toulson, delivering the judgment, referred to the general principle affirmed in Al Rawi that in a civil trial, just as in a criminal trial, the use of a closed material procedure was so alien to the right of a party to know the case advanced by the opposing party and to have a fair opportunity to respond to it as to be permissible only by Act of Parliament.
These proceedings were not a trial in the ordinary sense but a special form of statutory procedure. As a general proposition the court should not apply the Al Rawi principle to an application made by a party to litigation (or prospective litigation) to obtain evidence for the purpose of the litigation from somebody who is not a party or intended party to the litigation. Such an application would not ordinarily involve the court deciding any question of substantive legal rights as between the applicant and the respondent, rather, it was an ancillary procedure designed to see that evidence was made available to the court. Applications of this kind, such as an application for a witness summons were typically made ex parte.
The present situation, however, was different as the compulsory disclosure of journalistic material was likely to involve questions of the journalist’s substantive rights. Parliament had recognised this by establishing the special procedure under PACE. The appeal therefore turned on the meaning and effect of paragraph 7 of schedule 1 which requires the hearing to be inter partes. Upon making an application for a production order, a lis existed between the person making the application and the person against whom it was made, which might later arise between the police and the suspected person through a criminal charge. Equal treatment required that each should know what material the other was asking the court to take into account in making its decision and should have a fair opportunity to respond to it. This was inherent in the concept of an inter partes hearing.
Therefore it had not been permissible for the judge to hear part of the appellant’s evidence ex parte.
For the avoidance of doubt, Lord Toulson specified that the ruling did not prevent a court from hearing a public interest immunity application ex parte.