In its judgment, the Supreme Court confirmed that it is implicit in statutory schemes that montgomery_c_7_4_145779_rtwebcontemplate ex parte hearings, that is court hearings without notice held in the absence of interested parties, (in this case a Magistrates’ Court warrant granted under the Police and Criminal Evidence Act 1984, s 8), that the court may rely on information that is not disclosed to any interested party after the event, even if that information is vital to explain how and why the court made its order.

Lord Mance, who gave the only judgment, considered that any other result would render impracticable a statutory scheme in support of criminal investigations that was intended to operate speedily and simply in circumstances where the public interest required decisions to be taken on the basis of potentially sensitive sources of information [28].

Lord Mance considered that there were a number of protections, including the involvement of a judicial figure, the duty of candour and the fact that there was no issue directly between the police or prosecution and any person at issue in the application; he considered that an application under s 8 was concerned with premises and materials but not directly with persons [34, 36].

The Supreme Court held that it was implicit that any subsequent proceedings under the Criminal Justice and Police Act 2001, s 59 that might be concerned with a review of the search and seizure process, although ostensibly inter partes, that is on notice and in the presence of interested parties, could contain a closed material procedure in which material was considered by the court and withheld from disclosure to the interested parties.

The approach of the Supreme Court to the question of judicial review of any search warrant followed a similar pattern of reasoning. The Court recognized that judicial review would lack any real teeth if the Administrative Court could not hold a closed material procedure and, in the absence of any grounds for review on the face of the open material, would be bound to dismiss any application. Accordingly Lord Mance held that the only sensible conclusion was that judicial review can and must accommodate a closed material procedure, where that is the procedure which Parliament has authorised in the lower court or tribunal whose decision is under review [59].

This approach requires a degree of confidence in the operation of the statutory schemes in the magistrates’ and Crown Courts that may not always be reflected in practice in courts around the country. It is also difficult to understand how the operation of the duty of candour can be policed, even on closed material review given the range of material that will, of necessity, remain undisclosed on the strength of this decision. In modern circumstances where even core duties of disclosure are not observed due to lack of police or prosecution resources, it is hard to be confident that a more extensive duty of candour will be allocated sufficient resourcing to ensure it is complied with in the absence of any scrutiny by any interested party.

Although Lord Mance expressed the view that open justice should continue to prevail to the maximum extent possible and that as a minimum a case may require the disclosure of the gist of closed material in order for persons affected to understand the essence of the case against them where very significant personal interests, including liberty and important proprietary  rights were engaged [61- 63], he went on to observe that the short term invasion of property involved in the execution of search warrants did not require gisting in cases where prejudice to national interests might result.

Whether intended or not, these observations may encourage greater secrecy in relation to the processing of search warrants and other intrusive investigative orders. Questions will also remain about the effectiveness of judicial review in criminal causes or matters where PII is claimed since there must be real doubts as to whether a closed material procedure will be available at the permission stage so as to secure proper scrutiny of the legality of the decision where the application for judicial review lacks proof. Even in cases where permission is granted it is not clear whether the procedural protections available will be equivalent to those that are available in civil cases under the Justice and Security Act 2013, s 6.

The Supreme Court took some comfort from the fact that persons affected, if they were ultimately charged with a criminal offence, would be protected by fair and open criminal proceedings [64]. However this does not provide any certainty that any irregularities in the investigative processes will be identified or acted upon at that stage in the criminal process.  The powers of the criminal courts under of PACE, s 78 are limited in cases where the defence is not able to establish any irregularities in the investigative processes.