DB v Chief Constable of Police Service of Northern Ireland

Police operational discretion does not relieve the force of its common-law and statutory duty to prevent crime: where participation in an unnotified parade is a criminal offence (Public Processions (Northern Ireland) Act 1998 s.6(7)), the police have the power and duty (including under section 32 of the Police (Northern Ireland) Act 2000 and common law) to stop such parades, subject to proportionate assessment of public-order risks.

The appellant challenged the Police Service of Northern Ireland's (PSNI) handling of the 2012–13 "flags" protests in Belfast, arguing that PSNI failed to recognise and to use legal powers to stop weekly unnotified parades that caused disorder and infringed residents' rights. The claim began in the Northern Ireland High Court (Treacy J [2014] NIQB 55), which found a misapprehension of police powers; the Court of Appeal ([2014] NICA 56) allowed the Chief Constable's appeal. The Supreme Court considered whether PSNI misunderstood their powers under the Public Processions (Northern Ireland) Act 1998, the interaction with section 32 of the Police (Northern Ireland) Act 2000, and the relevance of Convention rights (notably article 11 and article 8), and whether operational discretion insulated the police from legal review.

1. Disposition: The appeal is allowed. The Supreme Court concluded that PSNI misconstrued their legal powers in dealing with the flags protests and that Treacy J was correct to find a material misapprehension.
2. Police powers and duties: The court held that participation in an unnotified parade is an offence under Public Processions (Northern Ireland) Act 1998 s.6(7), and that police possess both common-law powers to prevent crime and the statutory duty in Police (Northern Ireland) Act 2000 s.32 to prevent offences. Accordingly, the police have power to stop unnotified parades and a duty to consider doing so where appropriate (see paras 52–56, 63–66, 71).
3. Effect on the 1998 Act: The 1998 Act is not undermined by the police having recourse to common-law powers and s.32 to prevent unnotified parades; proper appreciation and enforcement of the notification requirement is central to the Act's operation (paras 62–66, 72).
4. Article 11 and spontaneous demonstrations: ECtHR authority shows that the absence of prior notification does not automatically invalidate Convention protection, but prior notification requirements are generally compatible with article 11; there is no general obligation to facilitate technically unlawful parades (see discussion of Eva Molnar v Hungary and related ECtHR authorities at paras 58–61). The Assistant Chief Constable’s view that article 11 obliged facilitation of technically illegal parades was misplaced (para 61).
5. Operational discretion and proportionality: Operational discretion is wide and important, but it is not absolute; it is subject to judicial review and a proportionality analysis where Convention rights are engaged. However, proportionality must be assessed in the correct legal context and cannot be divorced from whether police had an accurate appreciation of their powers (paras 71–76).
6. Appellate review of factual findings: The court endorsed caution in overturning first-instance factual findings and held that the Court of Appeal should have been more reluctant to reverse Treacy J, particularly given the documentary and affidavit material and the nature of the evaluation (paras 78–80).
7. Orders and final words: The Supreme Court reversed the Court of Appeal's decision, declared that PSNI misconstrued their powers in policing the flags protests affecting Short Strand, and allowed the appeal (para 81). The judgment emphasises clarity about the police's legal powers and the appropriate balance between preventing crime and managing public-order risk.

• Supreme Court: Appeal allowed; declaration made that PSNI misconstrued their powers (this judgment) — reversed the Court of Appeal.
• Court of Appeal (Northern Ireland): [2014] NICA 56 — allowed the Chief Constable's appeal against Treacy J (reversed by this court).
• High Court (Northern Ireland) - Queen's Bench: [2014] NIQB 55 (Treacy J) — granted relief and found police laboured under a material misapprehension regarding powers; decision partly reinstated by this court.