Martyn's Law glossary. Every term, in plain English.

Martyn's Law

The common name for the Terrorism (Protection of Premises) Act 2025, named after Martyn Hett, who was killed in the Manchester Arena attack in 2017.

Protect Duty

The name for the government's proposals before the law was called Martyn's Law. The government consulted on the Protect Duty in 2021, and in December 2022 said it would be known as Martyn's Law, in tribute to Martyn Hett. Read the guide

Qualifying premises

A building where 200 or more people can reasonably be expected at the same time, used for one of the purposes the Act lists, such as worship, entertainment, food and drink, or sport.

Standard tier

Premises where 200 to 799 people can be present at once. Places of worship, schools and childcare premises stay in this tier at any size.

Enhanced tier

Premises where 800 or more people can be present at once, with extra duties such as security measures.

Responsible person

The person or organisation in control of the premises, usually the committee, trustees, club or company that runs the building. They must make sure the duties are met. Read the guide

Public protection procedures

The plans the law asks for: evacuation, invacuation, lockdown and communication.

Evacuation

Getting everyone out of the building, or part of it, safely.

Invacuation

Bringing people inside, or to a safer place within the building, when the danger is outside. Read the guide

Lockdown

Stopping people getting in or out, for example by locking doors.

Communication

Telling people what's happening and what to do: stay where they are, or move away.

SIA

The Security Industry Authority, the regulator for Martyn's Law. It gives advice and can issue penalties.

Reasonably practicable

Doing what makes sense for your venue, weighing how much a step helps against its cost, time and difficulty.

Qualifying event

A public event where 800 or more people may be there at once, with a ticket, pass or membership check to get in, held somewhere that isn't already in the enhanced tier. It has its own rules. hailo doesn't cover these yet.

General information, not legal advice.