Magic Circle firms including Allen & Overy, Clifford Chance and Freshfields Bruckhaus Deringer are among 12 firms taking part in Diversity Lab’s UK pilot scheme to boost the number of lawyers from underrepresented groups in leadership positions.

Diversity Lab’s Mansfield Rule – which is entering its fifth year in North America – has seen participation grow by 90% this year with more than 49 new firms signed up to the latest certification process due in July, taking the total number of firms to more than 160. The UK expansion is the Lab’s first programme outside of the US and Canada, which is designed to hold firms to account for their level of diversity among senior lawyers.

Natalia Marulanda, Diversity Lab’s Mansfield Rule manager, said: “We have received many requests over the last few years to launch a UK version of the Mansfield Rule, so we are thrilled to work with an advisory group of leading talent experts at these firms to formulate a similar vision. We now have the opportunity to test these same principles, which have been incredibly effective in the US and Canada, in a new context with this group of trailblazing UK firms.”

Those joining the trio of Magic Circle firms include Bird & Bird, Bryan Cave Leighton Paisner, Clyde & Co, DLA Piper, Hogan Lovells, Taylor Wessing and the UK offices of Dechert, Mayer Brown and Reed Smith.

The Mansfield Rule 5.0 certification process introduces a number of new requirements for participating firms, including tracking candidate pools in a disaggregated manner to measure the impact of the rule by each underrepresented group. Firms must also add an option for Middle Eastern and North African identity and consider at least 30% underrepresented lawyers for nominations to the Chambers USA directory to increase the visibility of those lawyers.

Firms that are seeking ‘Mansfield Certification Plus’ – a recognition that they have achieved 30% representation of underrepresented lawyers across various Mansfield Rule categories – will also be asked to publish partner pay criteria and processes.

Marulanda said: “Increasing accountability and transparency have always been major objectives of the Mansfield Rule, and we’re excited to be working with firms to shed more light on partner compensation practices, the holy grail of inclusion and equity.”

In-house legal departments are also looking to improve diversity, within their own teams and among their outside counsel. Last month, Nokia’s legal team launched an equity, inclusion and diversity scorecard system to assess its six panel law firms, with the Mansfield Rule among the criteria used. And earlier in the year, Coca Cola unveiled a series of diversity targets for its US advisers with the threat that their ability to meet them will be a “significant factor” in determining whether they make its first-ever preferred panel of law firms next year.