Places of worship are in scope for Martyn's Law if their qualifying capacity is 200 or more. Many larger churches, mosques, temples and cathedrals will be Enhanced Tier.
The Terrorism (Protection of Premises) Act 2025 received Royal Assent in April 2025. Places of worship above the qualifying capacity threshold must comply before April 2027. The law applies to any faith tradition.
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01 / Which Tier
Cathedrals and large mosques are typically Enhanced Tier. Most local churches and smaller congregations fall below the threshold.
The Act applies to qualifying premises, defined by capacity. A place of worship with a maximum capacity of fewer than 200 people is not in scope at all. Most local parish churches, small mosques and community prayer rooms will fall below this threshold.
Larger places of worship, including most Church of England cathedrals, major Catholic churches, large mosques serving urban congregations, Sikh gurdwaras with significant community spaces, and Hindu mandirs with substantial main halls, will often exceed the 200-person threshold. Whether they fall into Standard Tier (200 to 799) or Enhanced Tier (800 or above) depends on the specific capacity of the main worship space and any attached community halls.
Many cathedrals that host concerts, graduation ceremonies or civic services will clearly meet the Enhanced Tier threshold. Large urban mosques serving Friday congregations that exceed 800 worshippers at peak will also fall into Enhanced Tier. The obligation applies regardless of the faith tradition.
- Documented evacuation and lockdown procedures
- Staff and volunteer training on terrorist threat response
- Communication protocols for an attack scenario
- SIA registration
- All Standard Tier obligations
- Documented vulnerability assessment
- Designated responsible person
- Active physical protective measures
- Demonstrable monitoring capability for SIA assessment
02 / What Measures
Places of worship face a unique security challenge: they are open by tradition and principle, but targeted precisely because of that openness.
The legislative history behind Martyn's Law is rooted in the Manchester Arena attack. But globally, places of worship have been the target of some of the most devastating terrorist attacks in recent years. The Pittsburgh synagogue attack in 2018, the Christchurch mosque attacks in 2019, and numerous attacks on churches across Europe and beyond demonstrate that religious venues are specifically targeted environments.
For in-scope places of worship, the Martyn's Law obligation is not just about ticking a regulatory box. It reflects a genuine and documented threat pattern. Standard Tier venues need procedures. Enhanced Tier venues need physical measures that can actively detect and create an opportunity for intervention.
AI behaviour detection is the proportionate response for Enhanced Tier religious venues. It operates on your existing camera infrastructure without changing the physical or spiritual character of the building. Detection runs continuously, monitoring entrance areas, external perimeters and public spaces for the behavioural patterns associated with pre-attack reconnaissance and threat.
Open-access buildings have specific detection requirements.
Because places of worship are open to the public, controlling who enters is not typically practical. Active monitoring of behaviour within and around the building is the proportionate alternative.
Works within the character and constraints of historic buildings.
Many larger places of worship are listed buildings or in conservation areas. Archangel adds an AI detection layer on existing cameras without physical alterations to the building fabric or changes to how the space looks and feels.
Volunteer-run organisations can still comply.
Many religious venues are managed largely by volunteers. The designated responsible person obligation can be met by a senior volunteer, trustee or paid member of staff. The detection system runs continuously, without requiring a trained security operator.
03 / How AI Behaviour Detection Helps
What Archangel detects in and around a place of worship.
Loitering near entrances and external perimeter
Extended presence near building entrances or along the external perimeter is one of the clearest pre-attack reconnaissance indicators. Detection alerts the duty responsible person immediately.
Unusual approach patterns
Individuals who circle a building multiple times, approach and retreat from entrances, or remain in the vicinity for extended periods without entering are flagged for review.
Unattended items inside the building
Any item left unattended in the main worship space, entrance lobby or public areas is flagged in real time, allowing staff or volunteers to assess and respond immediately.
Aggression or threatening behaviour
Physical confrontation or threatening behaviour inside or immediately outside a place of worship is detected and flagged to the responsible person with the exact location and camera view.
Access monitoring for restricted areas
Many places of worship have restricted areas such as vestries, offices and storage rooms. Detection flags individuals who enter those areas without authorisation.
Documented detection log
Every alert, confirmed detection and staff or volunteer response is logged automatically. That log provides documented evidence of active monitoring when the SIA conducts its assessment.
For the full guide to Martyn's Law, including how qualifying capacity is assessed and what both tiers require, visit our main guide.
Read the full Martyn's Law guideFind out what Martyn's Law means for your place of worship.
Book a discovery call. We will assess your qualifying capacity, your existing camera infrastructure, and what active AI monitoring looks like for your specific environment. Two months free means you can start before enforcement begins.
Two months free. No hardware. No commitment beyond the conversation.