Leighton is the founder of Leighton Cassidy Legal, established in 2026. Prior to returning to live and practice in New Zealand in 2023, Leighton was a partner in an international law firm based in London, England. Leighton spent over 20 years in the UK and was co-head of the intellectual property team from 2013. He was recently a consultant in a NZ law firm.
Leighton is admitted in New Zealand (1997) England & Wales (2006) and Ireland (2017). Leighton advises clients in relation to their intellectual property and commercial requirements. This includes worldwide trade mark and design clearance, filing and prosecution; contentious registry proceedings including bringing and defending trade mark opposition, invalidity and revocation actions throughout the world; appeals to the Appointed Person and High Court, appeals to the Boards of Appeal and General Court, trade mark licensing, exploitation and commercialisation; settlement, co-existence agreements and dispute resolution; appeals to the HIgh Court and Court of Appeal in New Zealand, managing intellectual property litigation internationally.
Leighton is internationally recognised in the legal directories including the Legal 500, Who’s Who, Managing IP, World Trademark Review. Leighton and his team are a past winner of Managing IP's Firm of the Year, Trade Mark (Law Firms)
Leighton is a past committee member of The University of Otago Trust (UK), a UK based charitable trust since 2014 and current Chair of the Otago University Rugby Football Club. He is also sits on the NZURFC committee and is an alternate Director for the Highlanders super rugby team.
He sits on the Indigenous Rights Committee of the International Trademark Association (INTA) and regularly attends their annual and leadership meetings. He is a member of IPSANZ and Business South.
Recommended Individual “...Leighton Cassidy brings deep international expertise to brand protection and enforcement, shaped by two decades in the UK guiding high-value trademark matters. He advises on worldwide filing strategies, registry proceedings and commercial exploitation of rights, as well as coordinating multinational litigation and negotiated settlements for diverse rights holders.”
WTR1000 2026
"Leighton Cassidy excels in advising client on intellectual property and commercial matters. His expertise spans global trademark and design clearance, contentious proceedings, appeals, licensing, and international IP litigation.”
WTR1000 2025