Multiplex Construction Europe Limited v Persons Unknown

A final injunction against persons unknown may be granted, but the power does not remove the need for authorised notification and a proper final procedure. An interim injunction requires assessment of at least 13 factors, including a pleaded cause of action, evidence of realistic success, potential defences, the balance of justice, adequacy of damages, clear definition of the persons and prohibited conduct, proportionate terms, clear boundaries, limited duration, authorised service, a right to set aside or vary, and review where final orders are made. The order must not catch mere vagrants or trespassers. Where high climbing creates a substantial risk of grave injury or death, that risk can justify interim restraint and damages may be inadequate.

The claimants sought a final prohibitory injunction, lasting until February 2027, against persons unknown entering or remaining on a construction site without permission. The application followed a series of interim injunctions and extensions made since July 2020. The evidence concerned urban explorers climbing cranes and other high structures, creating risks to them, site workers, security staff, emergency services and the public.

The court considered whether a final order could be made without authorised alternative service or participation by affected persons, and, if not, whether a further interim injunction should be granted.

Disposition. The application for a final injunction was refused. A further interim injunction was granted. There were no costs on the application.

1. Final injunction. Following Wolverhampton Council & Ors v London Gypsies and Travellers [2023] UKSC 47; [2024] 2 WLR 45, the court held that final injunctions against persons unknown are available, but the power does not override the need to notify affected persons and bring a proper final hearing before the court. Summary judgment or a duly notified final hearing could provide an appropriate procedure. Neither had occurred, and it was improper to determine the final application ex parte without authorised alternative notification.
2. Interim framework. The court identified at least 13 factors governing an interim injunction against persons unknown. These included the cause of action, evidence of realistic success, potential defences, balance of convenience, adequacy of damages, identification of the persons and conduct, clarity and proportionality of the terms, conformity with the pleaded claim, geographical limits, duration, service, set-aside or variation rights, and review requirements for final orders.
3. Application of the factors. The claim identified trespass allied to climbing and the evidence established a realistic prospect of success. Potential Convention-rights defences were considered. The relief concerned conduct on the claimants’ land, and the court held that freedom of speech and assembly rights were not engaged. Continuation of the interim injunction did not breach s.12(3) of the Human Rights Act.
4. Risk and remedy. The ordinary balance of convenience applied to the interim application. The substantial risk of grave injury or death to climbers, workers, security staff, emergency services and the public provided compelling justification even if a higher threshold applied. Damages were not an adequate remedy for severe personal injury. The court had also read Mace v Persons Unknown [2022] EWHC 329, which summarised the general risks of urban exploring.
5. Scope and terms. The persons unknown had to be defined by the prohibited tortious conduct and clear geographical boundaries. The order was narrowed to trespass or remaining on the site plus climbing, so that it did not extend to mere vagrants or trespassers. The prohibitions were stated in clear, non-technical terms and were sufficiently proportionate and site-specific.
6. Duration and safeguards. A final injunction should last only as long as reasonably necessary on the evidence. Approximately one year was appropriate for the further interim order. Alternative service must be considered and sanctioned by the court for a final hearing, while ex parte procedure was appropriate for the interim application. Persons unknown were given a short-notice right to apply to set aside or vary the injunction.
7. Review. Final orders in persons-unknown cases are quasi-final and require future review, with regularity depending on the circumstances. The court did not need to determine that issue because it was granting a further interim order.

This was a first-instance application. The judgment records interim injunctions and extensions from July 2020, including a temporary extension by Jefford J to the hearing date, but states no appeal.