William Long
UK Guide 2025
Band 3 : Data Protection & Information Law
Email address
[email protected]Contact number
+44 20 7360 2061Share profile
Band 3
About
Provided by William Long
Practice Areas
WILLIAM LONG is global co-chair of Sidley’s highly ranked Privacy and Cybersecurity practice and heads the EU Data Protection group. He is also a member of the firm’s top-ranked Crisis Management and Strategic Response team, and he serves on the Steering Committee of the firm’s AI Working Group. William advises international clients on a wide variety of AI, GDPR, cyber incident, data protection, privacy, information security, social media, e-commerce, and other regulatory matters.
William has been a member of the European Advisory Board of the International Association of Privacy Professionals (IAPP) and on the DataGuidance panel of data protection lawyers. He also founded and assists with dplegal (“data privacy” legal), a networking group of in-house lawyers in life sciences companies examining international data protection issues.
Publications
William is also the author of a book on the EU General Data Protection Regulation and a contributor to a number of books on data protection, including leading legal textbooks published by BNA in the area of privacy, cloud computing and the use of health data. William has been interviewed widely for his thought leadership, including in such leading publications as the international New York Times, Financial Times and The Guardian and writes for a number of publications, including Thomson Reuters, Law360, and Global Data Review.
Chambers Review
UK
William Long is the global co-chair of Sidley Austin's Privacy and Cybersecurity practice and heads the EU Data Protection group. He is a respected data protection and cybersecurity practitioner, well versed in compliance, processing, transfers and breaches.
Contributions
Latest contributions provided by William Long
Strengths
Provided by Chambers
"His advice is always clear and actionable."
"William has very strong expertise and is highly trusted."
"He is an expert who is very pragmatic in his approach. He has a very good ability to take a risk-based approach as he has good anticipation and foresight of what regulators might think."
"His advice is always clear and actionable."
"William has very strong expertise and is highly trusted."
"He is an expert who is very pragmatic in his approach. He has a very good ability to take a risk-based approach as he has good anticipation and foresight of what regulators might think."