"Ian always provides excellent advice and is very responsive." "He is excellent."

Chambers UK 2023


Ian McDonald is co-leader of Mayer Brown’s global Litigation & Dispute Resolution practice and a member of the firm’s global Cybersecurity & Data Privacy practice, based in London.

He acts for banks and funds, particularly in high value disputes relating to loan structures, structured finance and derivatives, many of which have cross-jurisdictional elements and often managing large teams and competing priorities. Ian has experience leading the UK litigation aspects as part of a cross-office, cross-practice team advising a financial institution on a cybersecurity incident. He has also advised on cases for financial institutions involving allegations of mis-selling, misconduct, misrepresentation, deceit, fraud, breach of duty, contractual interpretation and breach of transactional documentation, as well as on matters of enforcement, rectification and restitution. He is co-leader of the firm’s International Banking and Financial Litigation Action Group. Ian also acts for licensed insolvency practitioners, noteholders, lenders, creditors, directors and borrowers in contentious insolvency matters.

He joined Mayer Brown in 1990.


  • Englisch


  • Acted for the majority vote of the ISDA Determinations Committee in respect to the External Review of whether there had been a credit event in respect of Novo Banco.
  • Advising a global financial institution in relation to a data breach. Obtaining appropriate urgent injunctive relief against persons unknown responsible for the theft of data and implementing international process for compliance with notification and other obligations pursuant to GDPR and other relevant international standards.
  • Advising UBS in respect of claims relating to synthetic CDOs and related credit default swaps, including jurisdiction challenge and related proceedings in Germany
    UBS AG, London Branch & Anor v Kommunale Wasserwerke Leipzig GmbH [2010] EWHC 2566 (Comm), [2010] NLJR 1492, [2010] All ER (D) 176 (Oct).
  • Advising Spanish real estate investment fund in litigation concerning breaches of loan documentation including material adverse change and the construction of a London hotel and successful outcome after 9 week trial
    Grupo Hotelero Urvasco SA v Carey Value Added SL (2012) QBD (Comm) (Court of Appeal – 12 October 2012).
    Grupo Hotelero Urvasco SA v Carey Value Added SL [2013] EWHC 1039 (Comm).
  • Acting as Representative Defendant on behalf of Noteholders in a claim relating to a securitisation structure involving a major international bank.
  • Advising a bank in respect of a claim arising from a commodities based fraud
    Standard Bank Plc v Via Mat International Ltd & Anor [2013] EWCA Civ 490 (3 May 2013).
  • Advising UBS in the defence of a claim relating to split capital investment trusts
    Real Estate Opportunities Limited v. Aberdeen Asset Managers Jersey Limited, Aberdeen Asset Managers Limited, UBS Limited [2007] EWCA Civ 197, (2007) 2 All ER 791, (2007) Bus LR 971, (2008) 2 BCLC 116, Times, April 6, 2007, [2007] All ER (D) 161 (Mar).
  • Representing a leading global bank in a $6 billion claim for fraudulent trading brought by the Liquidators of BCCI.
  • Advising Trustees of a Dutch bank on claims arising from the termination of various swap contracts.
  • Advising junior noteholder on claims arising from RMBS securitisation of Portuguese residential mortgages
    Cinnamon European Structured Credit Master Fund v Banco Commercial Portugues SA [2009] EWHC 3381 (Ch); [2010] All ER (D) 209; (2009) 160 NLJ 30; [2010] I.L.Pr. 11.
  • Acting for portfolio manager in respect of claims for alleged mismanagement of portfolio.
  • Advising lenders and investors in various Structured Investment Vehicles, including role on Senior Creditors’ Committee of Cheyne Finance plc.
  • Advising Liquidators of a group of Cayman hedge funds in respect of claims against the management and administrators of the funds.
  • Advising Liquidators of Robin Symes Limited in antiquities-related claims involving foreign Governments 
    Phillips & Ors v Symes & Ors [2006] EWHC 2595 (Ch), [2008] BPIR 212, [2006] All ER (D) 170 (Oct).


University of Cambridge, Jesus College


  • England und Wales


  • The Association of Regulatory & Disciplinary Lawyers
  • Band 4: Banking Litigation. Ian McDonald has a great deal of experience in handling complex banking disputes. He is regularly engaged by major banks and funds for assistance with high-value cross-border litigation relating to issues such as financial mis-selling and breaches of contract. "Ian always provides excellent advice and is very responsive." "He is excellent." (Chambers UK 2023).
  • Listed in the Hall of Fame for Banking Litigation and as a key lawyer for Financial Services, Ian is praised as ‘charming, careful, reassuring and experienced’. He is also recommended for Commercial Litigation (Legal 500 2023).
  • A notable practitioner for litigation and banking litigation, Ian McDonald is a key contact. He has a great deal of experience in handling complex banking disputes. He is regularly engaged by major banks and funds for assistance with high-value cross-border litigation relating to issues such as financial mis-selling and breaches of contract.(Chambers UK 2022).
  • Listed in the Hall of Fame for Banking Litigation, Ian 'provides the firm’s clients with clear strategic direction and consistently displays exceptional judgment'. He ‘provides excellent and thoughtful advice regarding potential litigation and during actions (where such is required). He demonstrates a thorough approach to risk and commercial attitude.’ (Legal 500 2022).
  • Listed as a key lawyer for Fraud, he is 'not afraid to get into the detail of a case but also provides excellent strategic overview’. (Legal 500 2022).
  • Ian McDonald  has a great deal of experience in handling complex banking disputes. He is regularly engaged by major banks and funds for assistance with high-value cross-border litigation relating to issues such as financial mis-selling and breaches of contract. "Ian is immensely experienced. He knows the law and knows where to bring commercial realities into his approach." "He makes sure clients go in completely aware of the risks and how to present their case in a way that makes the difference between winning and losing." (Chambers UK 2021).
  • Listed as a 'Leading individual' for Banking Litigation. ‘Ian McDonald shows subtle and effective leadership. He is a highly intelligent partner, who is extremely proficient at managing large litigation. He is also a pleasure to work with’. Also listed under 'Other key lawyers' for Corporate Restructuring & Insolvency. (Legal 500 2021).
  • Listed as a 'Leading Individual', Ian McDonald co-heads the firm's global litigation and dispute resolution group. He has extensive experience of litigation relating to banking and financial services, including payment disputes, mis-selling allegations and breaches of contract. Sources praise his "brilliant judgement" as well as his management skills, saying: "He always maintains focus on the case and is excellent at structuring the team, being decisive and delegating where necessary." (Chambers UK 2020).
  • Listed as a 'Leading Individual' for banking litigation and under 'Other key lawyers' for fraud and corporate restructuring and insolvency. (Legal 500 2020).
  • Ian McDonald co-leads the firm's global litigation and dispute resolution practice and is experienced in handling big-ticket disputes for banks and fund clients. He has experience advising on cases pertaining to alleged mis-selling, misrepresentation, breach of duty and fraud. He is described by sources as "an extremely impressive partner who is a pleasure to work with and who is fantastic at managing the complex dynamics of large banking litigation." (Chambers UK 2019).
  • "Has great legal judgement and commercial acumen, and is a real team player who at the same time knows how to lead a team". (Legal 500 2018). 
  • Ian McDonald handles high-value, cross-border disputes concerning derivatives, structured finance transactions and loan structures. His expertise covers allegations of mis-selling, misconduct and fraud, among others. Clients say: "Ian combines good legal knowledge with an ability to understand what a client wants." (Chambers UK 2018).
  • Ian McDonald is "charming, engaging and a pleasure to work with" and "extremely proficient at managing complex litigation". (Legal 500 2017).
  • The "hugely personable" Ian McDonald is widely praised by clients and peers alike for being "very good at managing different personalities and egos in big cases and very experienced with banking work." (Chambers UK 2017).
  • "intelligent and well-organised" "gets to grips with disputes" (Legal 500 2016). 
  • "Strategic thinker" Ian McDonald is highly regarded in the market for his experience acting for bank and fund clients. He advises on a range of financial issues ranging from structured finance transactions to allegations of mis-selling and misrepresentation. (Chambers UK 2016);
  • Recommended. Ian McDonald "knows what clients wish to achieve in proceedings" (Legal 500 2015).
  • Head of department Ian McDonald is a key contact and is noted for his ability to balance getting into the detail of a case with his management of the team. Sources call him "a very experienced strategic thinker." (Chambers UK 2015);
  • "outstanding" and an "experienced, first-rate litigator" (Legal 500 2014);
  • "Ferociously intelligent and extremely practical," Ian McDonald consistently impresses peers, counsel and clients. Sources say he "immerses himself in the detail of the case" and is "absolutely exceptional at tactics and leading a team." Ian McDonald is recognised for being "calm, disciplined, great with clients and demonstrating excellent judgement." As head of the commercial dispute resolution team he is a solid option in contentious insolvency matters. (Chambers UK 2014);
  • Ranked as a key name, sources say Ian “has a real flair for banking litigation” (Chambers UK 2012);
  • He is "clear thinking" and "superb" (Legal 500 2012);
  • A "very capable banking litigation lawyer - calm, thorough, experienced and with excellent judgement" (Legal 500 2011);
  • He "is clearly a heavyweight on the academic side, but he doesn't inflict that on you; instead he comes up with commercial solutions" (Chambers UK 2011);
  • He has "a cool temperament and keen intellect" and wins further client praise for his open and approachable demeanour (Chambers UK 2010);
  • "excellent" and "very strong both in terms of legal analysis and commercial outlook" (Legal 500, 2010);
  • He has a fine reputation and is "solid and calm" (Legal 500, 2009);
  • Ranked as a leading individual by Chambers & Partners UK Directory 2009 the "highly intelligent" Ian McDonald is "great for the nitty-gritty, nuts and bolts part of the law";
  • He offers "common sense advice" (Legal 500, 2008);
  • He "is respected for being 'extremely bright, with a sound knowledge of complex situations'" (Chambers UK 2007);
  • His "understanding of technical issues is second to none" (Chambers UK 2006);
  • He was also highly rated for his "quality of service and efficiency" (Legal 500 2004).