Jonathan Lafferty

JONATHAN LAFFERTY is a solicitor advocate in Sidley’s London office. His practice focuses on complex, high-value litigation and arbitration and other dispute resolution, often with a cross-border or international element.

Jonathan acts for clients in a wide range of industries, including private equity houses, global financial investors, automotive manufacturers, oil and gas majors, industrial manufacturers, auction houses, pharmaceutical clients, and technology and entertainment companies.

His experience extends across a broad range of commercial disputes, including share sale and shareholder agreements (especially warranty disputes and where fraud is alleged, enforcement of security, company directors’ duties and shareholder rights, pharmaceutical and technology licences, international sale and purchase agreements, and contentious sanctions issues. He has acted in multi-jurisdictional disputes involving breach of contract, allegations of oral contracts, and professional negligence, and his work has included the leading English authorities on the formation of oral contracts and also on the duties of an auction house to a consignor.

Jonathan has a particular focus on collective redress litigation. He has acted for defendants to some of the UK’s leading consumer action claims including cases involving product liability and securities litigation. Jonathan has also supported those clients in coordinating the defense of parallel proceedings in other jurisdictions, including in Scotland, Ireland and Europe.

Jonathan has extensive experience of contentious insolvency proceedings, including both corporate insolvency and personal bankruptcy proceedings. Jonathan has also acted for clients seeking to enforce their intellectual property rights in respect of trade secrets, patents, trademarks, and copyright. He advises on contentious employment and benefits issues, including managing the enforcement of confidentiality and non-compete covenants.

In addition to his contentious work, Jonathan regularly provides transactional support. He has particular experience in conflicts of laws and jurisdiction. Jonathan also advises litigation funders on the structuring of their investments and mitigating the risk of adverse costs awards against them.

Jonathan is recommended in Financial Services: Contentious in Legal 500 UK 2026.

Prior to joining Sidley, Jonathan trained at a Magic Circle firm, qualifying as an associate in the firm’s Dispute Resolution department in 2015.

Examples of Jonathan’s work include advising:

• Funds managed by affiliates of Apollo Global Management, Inc. in the Sale of Summit Leasing, a leasing company in Slovenia and Croatia.
• Funds managed by affiliates of Apollo Global Management, Inc. in the acquisition of The Travel Corporation.
• Buckthorn Partners in its US$210 Million Sale of Coretrax to Expro
• A syndicate of institutional investors defending claims for breach of contract and fraud in the English High Court arising out of their disposal of a pharmaceutical company.
• A major international investment company in defending a claim in the English High Court alleging that it had entered into an oral contract precluding it from exercising its security rights as a mortgagee over subordinated loans worth €150 million.
• A major international investment company in defending a claim in the English High Court alleging that it had entered into an oral contract by which it agreed to sell its interest in subordinated loans worth €150 million.
• A pharmaceutical company defending collective proceedings in the English High Court brought in parallel to a U.S. class action regarding the same allegations of product liability.
• Defendants in a major group action proceeding in the English High Court, and related proceeding in Scotland, Northern Ireland, and the Republic of Ireland.
• A major international investment company as a bankruptcy petitioner against a high-net-worth individual who owed it €70 million.
• A private equity investor on protecting its minority shareholding in an entertainment industry company, including the presentation of an unfair prejudice petition and an interim injunction restraining a transaction.
• A pharmaceutical company in proceedings in the English High Court brought by it to restrain use of its trade secrets by a former business partner.
• A global retailer on allegations that its anti-money laundering efforts were inadequate and that it had breached UK financial regulations.
• A financial institution in relation to allegations of breaches of UK financial regulations.
• An auction house against allegations of negligence in the assessment of a painting sold as a copy of Caravaggio’s painting “the Cardsharps.”
• Fortress Investment Group on the acquisition of Punch Pubs & Co.
• KKR on its majority acquisition of Biosynth Carbosynth, a Swiss life sciences reagents and custom synthesis and manufacturing services company.
• Great Hill Partners in connection with its acquisition of Notonthehighstreet, a UK curated online marketplace.

Some of the above matters were handled prior to joining Sidley.

Jonathan maintains an active pro-bono practice and in November 2025 was recognized for his “outstanding contribution to pro bono” at the Pro Bono Week 2025 Parliamentary Reception and Awards. In addition, in September 2023 he was named a Legal Hero by The Law Society, one of the inaugural winners of the honor recognizing those who “embody the values of a solicitor” and have made a “demonstrable, lasting and tangible difference” to the lives of others.

He appears as an advocate for individuals dealing with appeals at the Asylum Support Tribunal and in the Family Court, and he provides ad hoc legal advice to individuals through various pro-bono clinics. In a leading case, Jonathan acted for a victim of human trafficking, seeking through the Employment Tribunal to recover an award from her captors.