Marcus Turner


Marcus is a member of the Markets Innovation Group, a group of lawyers and developers who are focused on the creation of innovative solutions for clients to meet large-scale legal and regulatory challenges.

Marcus is core member of A&O Shearman’s AI Group, a global team of lawyers advising G-SIFIs, life sciences, private capital firms, media companies, and other large corporates on legal and regulatory issues relating to generative AI. Marcus has a particular focus on advising businesses on how to manage legal risk and regulatory compliance through effective AI policies and governance.

As part of his work with the Markets Innovation Group, Marcus has experience creating and developing a number of tech-focused client solutions, with a particular focus on AI-enabled platforms for scalable document digitisation.

Previously, Marcus had experience advising large financial institutions on legal issues relating to IBOR transition and the impact on the cash and derivatives market globally, including a secondment to a leading global bank to assist their legal team in coordinating their global IBOR transition.

Marcus was previously in the Derivatives and Structured Finance practice. Marcus has experience of OTC derivatives products across various asset classes and works on a variety of hedging transactions, including hedging aspects of real-estate finance and project finance. Marcus spent time working in New York, during which he advised the ISDA Credit Derivatives Determinations Committee for the Americas.

Whilst working in Markets Innovation Group:

ContractMatrix was developed by MIG, a system that uses AI to enhance contract drafting, review and analysis. This involved the first ever collaboration to develop a software product between a law firm and Microsoft. This system is used extensively within the firm and also by clients.

We became the first law firm in the world to deploy generative AI at an enterprise level with the roll out of Harvey in November 2022.

These innovations received widescale coverage in press, including the Financial Times and other leading international publications.


Representative matters

Marcus' key AI advisory credentials include:

Sole legal advisor to Partnership on AI, the global AI organisation that sets standards around responsible AI deployment by businesses around the world and informs the standards for regulation of AI.

Member of core team that runs A&O Shearman’s AI Working Group, through which a syndicate of more than 70 global clients (including numerous G-SIFIs, life sciences, private capital firms, media companies, and other large corporates) receives syndicated advice on substantive legal questions and issues affecting businesses deploying generative AI (see further below).

Advised a U.S. G-SIFI on their global AI policy, including drafting their ethical AI principles, policy on use, and AI use case deployment framework.

Pro bono

Mentoring young people through the firm’s award-winning Smart Start programme.

Published Work

  • “Generative AI and Legal Risk” as a chapter of “Cyber Security: Law and Guidance (2nd Edition)”, London: Bloomsbury, publication end 2024



Admitted as solicitor, England and Wales, 2020


Oxford University AI Artificial Intelligence Programme, 2023

BA (Hons), History, University of Oxford, 2016

A&O Shearman was formed on May 1, 2024 by the combination of Shearman & Sterling LLP and Allen & Overy LLP and their respective affiliates (the legacy firms). Any matters referred to above may include matters undertaken by one or more of the legacy firms rather than A&O Shearman.