Andrew Tannenbaum

Andrew is a leading technology lawyer with more than two decades of experience in financial services, big tech, government, and national security. His practice sits at the intersection of cybersecurity, AI, and data privacy, where he advises global enterprises, boards, and senior executives on their most significant technology-related risks. Ranked in Chambers USA, Andrew counsels clients across the full lifecycle of cyber, AI, and data matters, from governance, deployment, and compliance to incident response, investigations, national security and geopolitical considerations, and emerging issues such as frontier and agentic AI risks. With his unique background combining senior in-house and government roles, Andrew brings a deep and first-hand understanding of the operational and practical challenges clients face navigating high-stakes and emerging technology risks in highly regulated industries. 

Prior to joining A&O Shearman, Andrew served as General Counsel for Barclays Execution Services, the global services company of the Barclays Group. In that role, Andrew led Barclays’ legal teams worldwide across all areas of technology and operations, including cyber, AI, data privacy, emerging technologies, intellectual property, operational resilience, third-party risk management, technology transactions, and crisis management. 

Andrew has pioneered cybersecurity and AI roles for lawyers at the top levels of industry and government. He was the first Chief Cybersecurity Counsel at IBM, where he founded one of the earliest global corporate cyber legal teams, and he was Barclays’ first global legal head of AI, cyber, and data. During a decade in government, Andrew served as the National Security Agency’s first Deputy General Counsel for Cyber and held prominent positions in the White House and Department of Justice. He has overseen hundreds of cyber incidents and data breach investigations at all levels of severity, guiding clients through cross-border crisis response and regulatory investigations. 

A trusted advisor to boards, C-suite executives, general counsels, CISOs, and technology leaders, Andrew provides practical, business-focused counsel in highly dynamic and operational environments. Recognized for his thought leadership, Andrew teaches cybersecurity, privacy, and government surveillance law at Columbia Law School, has testified before Congress on cybersecurity law, and has contributed to leading publications such as The Wall Street Journal and Harvard Business Review.