Martyn's Law glossary: the key terms in plain English
Martyn's Law comes with its own vocabulary — standard tier, invacuation, responsible person, notification — and most of it is simpler than it sounds. This glossary defines each term in a sentence or two, grouped so you can scan to the one you need. The law applies to qualifying premises where 200 or more people may reasonably be expected at the same time, and is expected to commence in Spring 2027.
Martyn's Law comes with a small vocabulary of its own, and a lot of it sounds heavier than it is. This is a plain-English reference: skim to the term you need, or read it through once to get your bearings. Each entry is a sentence or two, and we link out to the fuller guides where there's more to say.
The basics
Martyn's Law — the common name for the Terrorism (Protection of Premises) Act 2025, named after Martyn Hett, one of 22 people killed in the 2017 Manchester Arena attack. It requires certain publicly accessible premises to be prepared for the possibility of a terrorist attack.
Terrorism (Protection of Premises) Act 2025 — the Act's formal name. "Martyn's Law" is the everyday term for the same thing.
Commencement — when the law takes legal effect. It is expected in Spring 2027; the Home Office has confirmed it will not be before April 2027.
Scope and tiers
The 200 threshold — the law applies to qualifying premises where 200 or more people may reasonably be expected to be present at the same time. That means realistic attendance, counting everyone — public, staff and volunteers — not the maximum on the fire-capacity sign. Our free scope checker walks you through it.
Qualifying premises — premises that are in scope: the public can access them, they have a qualifying use, and the 200 test is met. If any of those three isn't true, the premises are out of scope.
Standard tier — premises where 200 to 799 people may be expected at the same time. The duties are to notify, to have the four procedures, and to make sure people know them. There are no physical measures. Our guide to the standard tier covers it in full.
Enhanced tier — premises where 800 or more people may be expected at the same time. This adds further duties — public protection measures, documentation, and a designated senior individual. It is not the focus for community venues.
Worship and education carve-out — places of worship and most education settings are standard tier regardless of capacity. A large cathedral, for example, stays in standard tier whatever number it can hold.
Qualifying event — a separate route into scope. An event expecting 800 or more attendees, with conditions on entry such as tickets or checks, can qualify even at premises that wouldn't otherwise be in scope. It carries enhanced-tier-style duties and is distinct from the premises test. See our guide to events.
The four procedures
Public protection procedures (the four procedures) — evacuation, invacuation, lockdown and communication. They are the heart of standard tier, and they must be workable and known by the people who run the venue. Our standard-tier guide sets them out.
Evacuation — getting people out of the premises safely.
Invacuation — bringing people inside, or moving them to a safer part of the premises away from the danger. It is the opposite of evacuation, and we explain it more fully in what is invacuation?
Lockdown — securing the premises to keep people away from the danger, such as locking doors and closing shutters.
Communication — telling the people on site what is happening and what they should do.
Public protection measures — physical and organisational security measures required at enhanced tier only. They are not required at standard tier, so most community venues never deal with them.
People and duties
Responsible person — the person or body in control of the premises in connection with its use. They carry the duties; for community venues this is usually the management committee or trustees. There's more in our guide to the responsible person.
Notification — telling the regulator you are in scope, once its free online system opens. It is a living duty: you update it when things change. There is no public register.
Coordination duty — where premises are shared or nested inside one another, the responsible persons must coordinate, so far as is reasonably practicable, so the arrangements join up.
Reasonably practicable — the standard for how far you must go. It means what is appropriate to your premises and realistic for you — sensible and proportionate, not perfection.
Enforcement
The SIA (Security Industry Authority) — the regulator for Martyn's Law. It has said its approach is advisory-first: guidance and warnings come before penalties.
Compliance notice — a formal notice from the regulator requiring you to put something right. Our guide to penalties and enforcement explains where it sits.
Civil penalty — a financial penalty, up to £10,000 at standard tier, used as a backstop for venues that won't engage. The regulator's approach is advisory-first, so it is not an opening move; the same penalties guide has the detail.
Met a term that isn't here? The fuller picture lives in our guides to the standard tier, the responsible person and penalties and enforcement — or start with the scope checker to see whether any of it applies to you.
Common questions
What are the four procedures under Martyn's Law?
Evacuation (getting people out of the premises safely), invacuation (bringing people inside or to a safer part of the premises, away from the danger), lockdown (securing the premises to keep people away from danger), and communication (telling the people on site what is happening and what to do). Together they are the heart of standard tier, and they must be workable and known by the people who run the venue — not just written down and filed.
What's the difference between standard and enhanced tier?
Standard tier covers premises where 200 to 799 people may reasonably be expected at the same time; its duties are to notify the regulator, have the four procedures, and make sure people know them — no physical measures. Enhanced tier covers premises where 800 or more may be expected and adds further duties, including physical security measures, documentation and a designated senior individual. Places of worship and most education settings are standard tier whatever their size.
What does 'responsible person' mean?
The responsible person is the person or body in control of the premises in connection with its use — for community venues this is usually the management committee or trustees. They carry the duties under the law. There is more detail in our guide to the responsible person.
Now you know the words — are you in scope?
Our free scope checker walks you through the 200 test in three minutes, no sign-up. And if you'd like one plain-English email a month between now and commencement, join the countdown list.