Martyn’s Law: key terms explained

The legislation and guidance use a precise vocabulary. These are the terms that matter, defined as the Act and the Home Office statutory guidance use them.

Aligned to NaCTSO guidance · Last updated 2026-06-12

Martyn's Law

The common name for the Terrorism (Protection of Premises) Act 2025, named after Martyn Hett, killed in the Manchester Arena attack on 22 May 2017. Read our plain-English guide.

Qualifying premises

A building (or building and land) wholly or mainly used for one or more public-facing activities listed in Schedule 1 of the Act, where it is reasonable to expect 200 or more individuals, including staff, to be present at the same time at least occasionally, and which is not excluded under Schedule 2.

Qualifying event

An event at premises not otherwise in the enhanced tier where 800 or more individuals, including staff, are reasonably expected at the same time at some point, and entry is controlled by tickets, payment, passes or membership checks. Qualifying events carry enhanced tier duties.

Standard duty

The duties applying to qualifying premises expecting 200 to 799 individuals: notify the SIA and have public protection procedures (evacuation, invacuation, lockdown, communication) in place so far as reasonably practicable. See the standard tier guide.

Enhanced duty

The duties applying to qualifying premises expecting 800 or more individuals, and to qualifying events: the standard duty plus public protection measures, a compliance document provided to the SIA, and a designated senior individual. See the enhanced tier guide.

Responsible person

The individual, organisation or company in control of qualifying premises in connection with their Schedule 1 use, or of a qualifying event. The responsible person carries the duties under the Act.

Designated senior individual

Where the responsible person for enhanced duty premises or a qualifying event is not an individual, a senior person involved in managing the premises must be designated as responsible for ensuring compliance.

Public protection procedures

The four types of procedure required of all qualifying premises: evacuation, invacuation, lockdown and communication. See how to write them.

Public protection measures

The additional measures required of enhanced duty premises and qualifying events, covering monitoring, movement of individuals, physical safety and security, and security of information.

Evacuation

Moving people out of the premises and away from danger.

Invacuation

Moving people away from danger to a safer place within the premises, used when the threat is outside the building.

Lockdown

Securing the premises to prevent people entering or leaving, for example by locking doors and moving people away from access points.

So far as reasonably practicable

The legal standard applied to procedures and measures under the Act: what is appropriate for the particular premises, weighed against the cost, time and effort involved.

SIA (Security Industry Authority)

The regulator for Martyn's Law. A new regulatory function is being established within the SIA to support and guide responsible persons, with enforcement powers for serious or persistent non-compliance. See preparing for enforcement.

NaCTSO

The National Counter Terrorism Security Office, a police unit that publishes protective security guidance for the public and businesses, including through the ProtectUK platform.

ProtectUK

The national platform for counter terrorism protective security advice, guidance and free training, run in partnership with NaCTSO.

Compliance document

The document enhanced duty premises and qualifying events must prepare and provide to the SIA, recording their public protection procedures and measures and how these reduce vulnerability and risk of harm.

Compliance notice

A formal notice the SIA can issue requiring a responsible person to remedy specified failures within a set period.

Restriction notice

A notice the SIA can issue in relation to enhanced duty premises or qualifying events restricting how they operate until failures are addressed.