From Protect Duty to Martyn's Law: what changed
Last reviewed:
If you've found older articles, checklists or PDFs talking about a "Protect Duty" with different numbers to the ones we use on this site, you haven't stumbled on a separate law. Protect Duty and Martyn's Law are the same initiative, and the numbers changed as it moved from proposal to final Act. Here's the short version of what happened and why it matters for anything you're reading now.
They're the same initiative
"Protect Duty" was the government's working name for this legislation during its 2021 public consultation, well before there was a finished Bill or a formal title. As the proposal moved through drafting, it became the Terrorism (Protection of Premises) Bill, and it's now law as the Terrorism (Protection of Premises) Act 2025. Along the way it also picked up the informal name Martyn's Law, after Martyn Hett, one of the victims of the Manchester Arena attack, in recognition of his mother Figen Murray's campaigning. See what is Martyn's Law for the Act itself, in plain English.
The timeline, roughly
- 2021. The "Protect Duty" public consultation runs, gathering views on the shape of a new duty for public premises.
- 2022–2023. The proposal is developed into a draft Bill, refined through further engagement and pre-legislative scrutiny.
- 2024–2025. The Terrorism (Protection of Premises) Bill passes through Parliament and receives Royal Assent, becoming the Terrorism (Protection of Premises) Act 2025.
See when Martyn's Law comes into force for where things stand now on the commencement timeline and what's still to be confirmed.
What changed along the way
The clearest, most consequential change is the standard-tier threshold itself. The original 2021 consultation and early proposals worked from a much lower figure, commonly cited at the time as around 100 people, before it was raised substantially by the time the Bill was introduced, settling at the 200-person standard-tier threshold that's in the Act as passed. If you're reading an older checklist or explainer that still quotes a 100-person threshold, that's a strong sign it dates from the consultation era and hasn't been updated to reflect the final Act.
Other details firmed up later too: the Security Industry Authority (SIA) as the regulator, the specific two-tier standard/enhanced structure, and the SIA notification and inspection process were all worked out in more detail as the legislation moved from consultation through drafting to the Act. Anything written before the Bill's later stages is unlikely to reflect these in their current, final form.
How to spot stale "Protect Duty" advice
A quick checklist for anything you're reading that predates this site:
- Does it call the legislation a "Bill" rather than an "Act"? If so, it predates Royal Assent.
- Does it use a 100-person threshold instead of 200 for the lower tier? That's consultation-era, not current.
- Does it name the SIA as the regulator, or is the regulator vague or unnamed? Older material often predates this being settled.
- Does it cite a specific commencement date with confidence? Treat any firm date with caution until it's confirmed via the current timeline.
If an article, PDF or checklist trips more than one of these, treat it as a historical snapshot rather than current guidance, and check the current numbers against our guides or the official statutory guidance directly before relying on it.
Where to go from here: what is Martyn's Law for the Act as it stands today, and when it comes into force for the current commencement position.
Common questions
Is there a separate "Protect Duty" law as well as Martyn's Law?
No. "Protect Duty" was the working name used during the government's 2021 consultation, before the legislation had a formal title or a finished Bill. There is no separate Protect Duty Act sitting alongside Martyn's Law; they are the same initiative at different stages of the same process.
How do I know if something I'm reading is out of date?
A few quick tells: it calls the legislation a "Bill" rather than an "Act", it uses a 100-person standard-tier threshold instead of 200, or it doesn't mention the SIA as the regulator at all. Any of those is a strong sign you're reading consultation-era or draft-Bill material rather than the Act as passed.
About this guide. Written by the Martyn's Law Plan team, based on the statutory guidance published under the Terrorism (Protection of Premises) Act 2025. Last reviewed: . Read the official guidance on GOV.UK.
Sources: Terrorism (Protection of Premises) Act 2025; Home Office statutory guidance (April 2026, updated May 2026) and supplementary documents. Paragraph references are to the statutory guidance. General information, not legal advice. Contains public sector information licensed under the Open Government Licence v3.0.