Ex-SFO Director Intervenes in UBS Defense Against Hayes’ $400m Lawsuit

David Green, the former Director of the UK’s Serious Fraud Office (SFO), has submitted a declaration to a US court defending UBS against a $400 million lawsuit filed by former trader Tom Hayes. Green stated that the decision to prosecute Hayes was made solely by the SFO and was not influenced by the investment bank.

Background and Context

The litigation marks the latest chapter in the long-running legal saga surrounding Hayes, a former derivatives trader whose previous conviction became a landmark case in global financial regulation. The $400 million civil claim alleges that UBS played a role in actions leading to his prosecution. This intervention by a former senior prosecutor is rare in such commercial disputes, highlighting the high stakes involved for the bank’s reputation and legal standing.

Key Figures and Entities

According to SFO records, David Green served as Director from 2012 to 2018, overseeing the agency’s most complex financial crime investigations. In his court filing, Green explicitly distances the bank from the prosecutorial process: “The decision to prosecute Mr. Hayes was made by me as Director of the SFO and could not have been made by UBS or any private party.” The filing directly challenges the narrative presented by Hayes, who is seeking substantial damages from his former employer.

Legal and Financial Mechanisms

The legal mechanism at play involves the separation of public enforcement powers and private corporate interests. Green’s declaration aims to establish a firewall, asserting that the prosecutorial discretion exercised by the state is immune from pressure by private entities. By intervening, Green seeks to undermine the plaintiff’s argument that the bank bore responsibility for the criminal proceedings that followed the trader’s activities.

International Implications and Policy Response

This case underscores the ongoing friction between US civil litigation systems and foreign criminal enforcement actions. As cross-border financial crime investigations increase, the extent to which private banks can be held liable for the subsequent regulatory actions of sovereign states remains a contentious legal frontier. The outcome of this lawsuit could influence how multinational financial institutions approach cooperation with authorities and manage legacy litigation risks.

Sources

This report draws on specialist legal market analysis and declarations filed in US court proceedings regarding the litigation between Tom Hayes and UBS.