Maziar Jamnejad

Maziar Jamnejad is an associate attorney in the London office of Gibson Dunn. He specialises in the regulation of large technology platforms: online safety and platform regulation, artificial intelligence and advertising law, and the investigations, competition and class action litigation that arise from them. He combines that legal expertise with hands-on experience as a technologist and as a leader in legal innovation.

AI and Digital Regulation and Governance: Maziar advises global technology companies – social media platforms, AI developers, and search and e-commerce providers – on EU and UK digital regulation, including the Digital Services Act, the Digital Markets Act, the Online Safety Act and the EU AI Act, and on advertising and defamation risk. He has a particular expertise in cybersecurity, has led a number of significant security engagements, and holds the NCSC-assured Cyber Incident Planning and Response certification.

Investigations and Regulatory Enforcement: Maziar acts for clients in technology-related regulatory investigations and enforcement, with a focus on witness and expert evidence. He has also led financial markets and competition investigations, and advised on sanctions and export controls. He has worked directly with the SFO, FCA, CMA and OFSI.

Technology and Legal Innovation: Maziar brings an unusually practical perspective to technology work. He has held technologist roles, including product roles at AI start-ups and scrum-mastering software development teams, and holds certifications in AI, data science and cybersecurity from Microsoft, Google and IBM. He was previously Global Head of Legal Innovation at a Magic Circle law firm and Senior Counsel (Innovation) at HSBC, where he designed and delivered modernisation programmes for legal departments and led the adoption of advanced legal technology.

Maziar was recommended for artificial intelligence in Legal 500 UK 2026. He is a regular speaker on AI and the law. His article with Sir Michael Wood, The Principle of Non-intervention (Leiden Journal of International Law, 2009), is widely cited, including in a State's pleadings before the International Court of Justice. Earlier in his career he was a policy adviser at HM Treasury, focusing on the Budget.

Maziar's representive experience includes:*

AI and Digital Regulation and Governance

• Advised a global social media platform on its annual Digital Services Act and Online Safety Act systemic risk assessments, owning multiple risk pillars (including misinformation and fundamental rights), developing quantitative scoring methodologies, leading the cross-functional client consultation, and taking over the mitigations analysis across the assessment at short notice.
• Advised a leading AI developer across multiple UK and EU mandates, including its most legally and technically complex regulatory questions.
• Advised an AI provider on the legal risks of expanding into defence-related government work in the UK, covering procurement, official secrecy and anti-bribery legislation.
• Designed a cross-jurisdictional regulatory monitoring programme for a global technology company, assessing the relative risk of online safety legislation across hundreds of product lines using a technology-enabled methodology.
• Advised a global technology company on cross-border machine learning risks under EU and English law.
• Advised a leading search provider on defamation risk arising from its AI products.
• Advised a UK regulator on the adoption of AI in its regulatory investigation methodology.

Investigations and Regulatory Enforcement

• Acted for a global social media platform in a European Commission investigation under the Digital Services Act into addictive design, leading the preparation of several expert reports on comparative compliance and behavioural economics, and contributing to reports on UI/UX and neuroscience. Built an AI review environment that assessed c.400 academic studies against 26 criteria within 24 hours.
• Acted for a global social media platform in a regulatory investigation under the Digital Services Act into election interference, leading its work on data preservation, analysis and discovery.
• Led the most technically complex workstreams in class action defence for a global technology company's digital content platform, including AI, harmful content detection, cybersecurity, app development and payments.
• Led evidence and data workstreams in a major investigation into a digital sales platform.
• Led review and AI workstreams in competition matters for a global hotel group and a UK housebuilder.
• As lead associate, ran the firm's largest-ever investigation, into market misconduct at a global bank, with particular responsibility for designing the systems for evidence review of 120 million documents by 500 lawyers.
• Led multiple investigations for investment banks and insurers into market abuse, insider trading, market manipulation, anti-bribery and sanctions, including negotiations with the SFO, FCA and CMA.
• Led hub-and-spoke cartel investigations into information exchange in sectors including FMCG, utilities and information media.

*Includes matters handled by Maziar prior to joining Gibson Dunn.

Capabilities

• Litigation
• Antitrust and Competition
• Artificial Intelligence
• Privacy, Cybersecurity, and Data Innovation

Credentials

Education:

• University of Cambridge - 2006 Master of Laws (LL.M.)
• University of Oxford - 2005 Master of Arts

Admissions:

• England & Wales - Solicitor