What Is Martyn's Law? The Complete Guide

The Origins of Martyn's Law

Martyn's Law is named after Martyn Hett, one of 22 people killed in the Manchester Arena bombing on 22 May 2017. After the attack, Martyn's mother, Figen Murray, campaigned for legislation that would require public venues to take basic steps to protect people from terrorist attacks. That campaign succeeded. The Terrorism (Protection of Premises) Act 2025 received Royal Assent in April 2025.

The Act creates a legal duty for venues and premises to have procedures in place that reduce the risk of a terrorist attack and limit harm if one occurs. Before this legislation, there was no consistent requirement for venues to plan for terrorism. Some did it well. Many did nothing at all. Martyn's Law changes that by setting a clear, enforceable standard.

Who Is In Scope

The Act applies to qualifying premises and qualifying events in the United Kingdom. A premises qualifies if it has a capacity of 200 or more people. This covers a wide range of venues: hotels, shopping centres, nightclubs, theatres, stadiums, places of worship, conference centres, leisure facilities, retail parks, and many more.

Capacity is based on the maximum number of people the premises can hold at any one time, including staff. If your venue can hold 200 people, you are in scope regardless of whether you regularly reach that number.

The Two-Tier System

Martyn's Law operates on a two-tier system designed to make requirements proportionate to risk.

Standard Tier (200 to 799 capacity): Venues in this tier must put in place public protection procedures. These are practical steps to reduce vulnerability and improve response if an attack happens. The focus is on planning, awareness, and basic preparedness. You do not need to install expensive equipment or hire dedicated security teams for this tier, but you do need documented procedures and trained staff.

Enhanced Tier (800+ capacity): Larger venues carry greater risk because they attract larger crowds. The enhanced tier requires everything in the standard tier plus additional measures. These include a formal risk assessment for terrorism, a security plan, and the implementation of reasonably practicable measures to reduce risk. This might include CCTV monitoring, access control, bag checks, vehicle mitigation, and staff training to a higher standard.

What "Proportionate" Means

The Act does not expect every venue to install airport-style security. The word "proportionate" appears throughout the legislation. What counts as proportionate depends on the nature of the venue, its location, the type of events it hosts, and its existing security measures. A village hall hosting occasional community events faces different expectations than a city-centre arena hosting sold-out concerts.

The principle is straightforward: do what is reasonable given your circumstances. If you run a mid-sized hotel, reasonable measures might include staff training on recognising suspicious behaviour, documented evacuation procedures, and monitored CCTV in public areas. You are not expected to deploy armed guards.

Key Requirements

For all in-scope premises, the Act requires:

• A designated "responsible person" accountable for compliance
• Public protection procedures (standard tier) or a terrorism risk assessment and security plan (enhanced tier)
• Staff training so that employees know what to do in an emergency
• Notification to the Security Industry Authority (SIA) that the premises is in scope
• Regular review and updating of procedures

The Implementation Timeline

The Act includes a 24-month implementation period from Royal Assent. This means enforcement is expected to begin around April 2027. The SIA will be the regulating body, responsible for overseeing compliance, conducting inspections, and taking enforcement action where necessary.

Two years sounds like plenty of time, but building proper procedures, training staff, conducting risk assessments, and implementing technology takes longer than most people expect. Venues that start planning now will be in a much stronger position than those that wait.

How AI Behaviour Detection Fits In

Technology is not required by the Act, but it is one of the most effective ways to demonstrate proportionate safety measures. AI behaviour detection systems can monitor existing CCTV feeds for suspicious activity, crowd density changes, aggressive behaviour, and other early warning signs. This gives security teams real-time awareness without requiring additional personnel on the ground.

For enhanced tier venues in particular, AI monitoring provides documented evidence that you are actively working to identify and respond to threats. That kind of evidence matters when the SIA comes to assess your compliance.