Martyn’s Law

Martyn’s Law is the Terrorism (Protection of Premises) Act 2025, which received Royal Assent in April 2025. It sets two tiers for premises based on how many people may be present, with an implementation period of at least 24 months before enforcement. The Act sets the tiers; physical security answers the protection it asks premises to consider.

• Royal Assent April 2025The Terrorism (Protection of Premises) Act 2025
• 200 to 799 peoplePremises in the standard tier
• 800 or morePremises in the enhanced tier
• Security Industry AuthorityThe regulator

What the Act is

Martyn’s Law is the short name for the Terrorism (Protection of Premises) Act 2025. It received Royal Assent in April 2025. It is concerned with the protection of premises and events against terrorism, and it introduces duties that depend on the size of the premises, measured by how many people may be present.

The Act works through two tiers. The standard tier covers premises where 200 to 799 people may be present. The enhanced tier covers premises where 800 or more people may be present, and qualifying events. The tier decides the level of duty, with the enhanced tier carrying the heavier requirements.

Two further facts frame the whole regime. There is an implementation period of at least 24 months before the Act is enforced, giving those responsible time to assess their premises and prepare. And the regulator is the Security Industry Authority. These are the headline facts; how the Act applies to a specific premises is a legal question, and you should take legal advice on it.

The two tiers

The tier system is the heart of the Act. It sorts premises by capacity, and the table below sets out the two tiers as the Act defines them.

The standard tier captures a wide band of everyday premises: shops, restaurants, places of worship, smaller venues and similar buildings where between 200 and 799 people may be present at one time. The enhanced tier captures the larger end: major venues, large shopping centres, transport interchanges and qualifying events where 800 or more may be present.

The distinction that matters for this site is in the enhanced tier. Enhanced tier premises must consider physical measures as part of their response to the Act. That is a duty to consider, not a shopping list, and it is where rated doors, glazing, entrance control and vehicle mitigation enter the conversation. The standard tier has its own duties, and the published guidance from the regulator is the place to check the detail for each tier.

The Act does not mandate specific products. Enhanced tier premises must consider physical measures, but the Act does not name products or ratings. The choice of measures follows from the risk assessment for the premises.

The implementation period

The Act provides for an implementation period of at least 24 months before it is enforced. That period is there so that those responsible for premises can work out which tier applies, understand the duties, and put measures in place in an orderly way rather than in a rush.

For anyone responsible for a premises, the sensible use of that time is assessment first and purchasing later. Establish how many people may be present and therefore which tier is likely to apply. Follow the guidance the Security Industry Authority publishes as the regime develops. Review the existing physical security against the threats the premises faces. Then, and only then, specify new measures where the assessment shows a gap.

Physical security projects take time: survey, design, manufacture and installation do not happen overnight, and rated products are made to order. Starting the assessment early means the physical measures, where they are needed, can be specified properly and installed without disrupting the operation of the premises.

The regulator

The regulator under the Act is the Security Industry Authority. The SIA is the body responsible for overseeing the regime, and its published guidance is the authoritative source on how the tiers, duties and timelines apply in practice.

Because the regime is new, guidance will develop during the implementation period. Those responsible for premises should follow the SIA’s publications rather than relying on summaries, including this one, for the detail. The facts stated here are the Act’s headline facts; everything else about duties, definitions and process sits with the regulator’s guidance, which specifiers should check for their project.

What “consider physical measures” means for your building

For enhanced tier premises, the Act requires physical measures to be considered. In practice that means looking at the building as an attacker would: the entrances, the glazing, the perimeter and the routes vehicles can take, and asking what would slow or stop an attack at each point.

Physical measures are one layer among several. They sit alongside procedures, staffing and planning, and they are chosen from the risk assessment, not from a catalogue. The product groups below are the ones specifiers reach for when the assessment points to the building fabric: security doors for entrance points, security windows and blast resistant glass for glazed areas, turnstiles and pedestrian speed gates for controlling the flow of people, and hostile vehicle mitigation with security bollards where vehicles are the threat.

The discipline is the same as any security specification. Define the threat, choose products tested to the relevant standards, and require the test evidence. Our vehicle impact ratings guide explains PAS 68, IWA 14-1 and ISO 22343-1 for anyone considering HVM, and the public spaces and transport hubs sector pages show how these measures fit real building types.

How to prepare: six steps

1. Establish the capacity. Work out how many people may be present at your premises at one time.
2. Identify the tier. Compare the figure with the thresholds: 200 to 799 for the standard tier, 800 or more for the enhanced tier, plus qualifying events.
3. Follow the regulator. Read the Security Industry Authority’s guidance as it is published during the implementation period.
4. Review the building. Assess entrances, glazing, perimeters and vehicle routes against the threats the premises faces.
5. Specify to standards. Where physical measures are needed, choose products tested to recognised standards and require the evidence.
6. Take legal advice. Confirm how the Act applies to your specific premises with a qualified adviser.

None of these steps requires buying anything on day one. The implementation period exists precisely so that assessment comes before procurement, and a measured programme will produce better security than a hurried one. Where the assessment does point to physical measures, our security consultancy and design services can help turn the findings into a specification.

Physical security products relevant to the Act

To repeat the key point: the Act does not mandate specific products. The products below are relevant because they are what a risk assessment for a crowded premises commonly points to, not because the Act names them.

For the building envelope: security doors rated to LPS 1175, security windows, and blast resistant glass where the assessment includes explosive threats. For controlling entry: turnstiles, pedestrian speed gates and security portals. For the perimeter: security bollards and the wider hostile vehicle mitigation range, tested to a recognised vehicle impact standard. Sectors already working through these questions include high-value retail, education and government and defence.

Frequently asked questions