What Martyn's Law obligations do law firms have?

Most law firms fall under the standard tier of Martyn's Law (premises with capacity for 200 to 799 people), and a substantial number of smaller firms sit below the 200-capacity threshold entirely and are out of scope. Only larger firms with all-staff event venues, training auditoriums or partner-conference suites are likely to cross into the enhanced tier at 800-plus capacity. The first practical step for any firm is a tier assessment to confirm where it actually sits, because the public-facing capacity calculation often surprises building managers and partnerships alike.

The capacity calculation is built around publicly accessible space, which for a law firm typically means reception, the visitor waiting area, ground-floor client meeting rooms and any conference or training space that's open to clients, panel members or the wider profession. Back-of-house partner offices, working floors and matter rooms are not generally counted as publicly accessible. Many firms get the calculation wrong by including total headcount or net internal floor area rather than the qualifying public-facing zones. Working through this properly is what a Martyn's Law assessment is for.

The decisive factor for City and West End firms is the coordination duty for shared-services buildings. Most flagship firms in EC1, EC2, EC3, EC4, WC1, WC2, W1 and around Canary Wharf occupy floors in multi-tenant landlord-managed buildings with a shared lobby, shared reception desk and shared evacuation infrastructure. Under the legislation the duty is shared between the firm (responsible for its own occupied floors and any space it controls) and the landlord or building manager (responsible for the lobby, common parts and building-wide procedures). Practical compliance work has to land on both sides; a firm-only assessment that ignores the landlord-managed lobby will leave gaps. We coordinate this directly with the building manager as part of the legal-sector compliance design.

For a typical mid-sized City firm the assessment outcome is: standard tier, a documented set of public protection procedures (evacuation, invacuation, lockdown, communication), staff training to a defined cadence, and a simple plan reviewed annually. For the smaller end of the market the outcome is often "below threshold and exempt", which is still worth documenting so the firm has a defensible audit trail if its profile changes.

Quick reference: most law firms are standard tier (200-799 capacity) or exempt below 200; enhanced tier (800+) only for larger firms with all-staff venues; coordination duty shared with landlord in multi-tenant City buildings; tier assessment first to confirm scope.