New Martyn’s Law guidance clarifies how to determine the principal use of multi-use premises

The Home Office has published new guidance to help organisations determine the “principal use” of premises that serve more than one function under the Terrorism (Protection of Premises) Act 2025, commonly known as Martyn’s Law. The guidance is intended to support those responsible for venues and premises in identifying who holds legal responsibility where multiple specified uses apply to the same site.

Published on 10 September 2026, the new Terrorism (Protection of Premises) Act: principal use of premises guidance explains how duty holders should determine the principal use of a venue in accordance with the Terrorism (Protection of Premises) (Principal Use of Premises) Regulations 2026. The regulations are due to come into force on 15 October 2026 and provide the legal framework for assessing premises with more than one specified use listed in Schedule 1 of the Act.

The guidance addresses a practical issue facing operators of mixed-use sites, such as venues that may function as both entertainment and hospitality premises, or buildings that host a range of public-facing activities. In such cases, determining the principal use of the premises is essential because it establishes who the “responsible person” is for the purposes of compliance.

Under Martyn’s Law, responsible persons for premises and qualifying events must take steps to be prepared for a terrorist attack and, in the case of larger premises, consider additional measures to reduce vulnerability to terrorism where appropriate. The Act introduces a tiered framework, with requirements varying according to the number of people it is reasonable to expect may be present at a premises or event.

The publication of the principal use guidance forms part of a wider programme of implementation support following the Act receiving Royal Assent on 3 April 2025. The government has published a collection of guidance documents covering key aspects of the legislation, including statutory guidance, notification requirements, factsheets and sector-specific advice.

According to the Home Office, the new guidance specifically explains how to determine the principal use of premises where two or more Schedule 1 uses apply. This determination is necessary for identifying the responsible person and ensuring duties under the legislation are assigned correctly.

The accompanying regulations, which take effect from 15 October 2026, are expected to provide greater legal certainty for operators of complex and multi-purpose premises as organisations continue preparations for the implementation of Martyn’s Law. Together, the regulations and guidance are designed to support consistent application of the Act and clarify accountability across venues that fall within its scope.

As implementation continues, the latest guidance provides another key piece of the compliance framework, helping venue operators, event organisers and other duty holders understand how responsibility will be determined where premises have multiple qualifying uses.