John Cassels | Fieldfisher
Skip to main content
Professional background

Professional background

I co-head the firm's Regulatory Group.  I specialise in competition law and risk management, advising on all aspects of the UK and EU regimes including cartel investigations, antitrust litigation, restrictive agreements, dominance issues, alliances, and structural changes such as mergers and acquisitions.  I also work with clients on public procurement, state aid, international trade and regulatory investigations. My advice is practical and commercial, focusing on assessing and mitigating real risks.    

I have worked with clients across a broad range of industries from water and wastewater to soft drinks. I have particular expertise in regulated sectors, including food/beverage, transport, life sciences and financial/professional services.

I have a First Class Honours Degree in Law from the University of Glasgow (Scotland) and a Masters in Law and Economics (Distinction) from the University of Rotterdam (The Netherlands).

 

Awards & recognition

Awards & recognition

Peloton Interactive, Inc.
John Cassels and the entire Fieldfisher team has been a valuable partner to us as we entered the European market. They are responsive and thorough, but most importantly they have really taken the time to understand our business, our goals, and our people, and the result is smart, practical advice even when we're moving fast. We think of them as an extension of our team and would happily recommend them
Legal 500
Very astute, approachable and adaptable

Authored pieces

All Resources
A digital representation of Earth with focus on Africa, showcasing a network of glowing points and interconnected lines. Surrounding the globe are various circular data trails and bright streaks, symbolizing global connectivity and data exchange.
Press Release

Fieldfisher hires Peter Hood to strengthen UK and EU regulatory offering

02.06.2026
Leading European law firm Fieldfisher is delighted to announce that Peter Hood has joined our Regulatory team as a partner in London.  
Learn more
Close-up of a person's hand with purple nail polish resting on the trackpad of an open laptop. The background is softly blurred with pink and blue tones. The person appears to be using the laptop, which is situated on a flat surface.
Public and Regulatory
Insight

No more faux five stars: CMA launches new fake reviews investigations

08.04.2026
Learn more
A close-up image of a metallic maze with smooth, polished surfaces. The maze is displayed in shades of purple and blue. A white arrow is seen pointing through the maze, indicating a path.
International Trade
Insight

NSIA consultation response

26.03.2026
Learn more
A digital world map is depicted with glowing blue dots representing continents on a dark background. Bright, multicolored bokeh lights are scattered across the image, adding a dynamic and futuristic feel.
Technology
Insight

9 tech sector trends for 2026: regulation, resilience and recalibration

28.01.2026
Learn more
Technology
Insight

7 key takeaways from Fieldfisher’s 2025 Tech Sector GC Summit

29.10.2025
As 2025 unfolds, the technology sector stands at a pivotal crossroads. Global markets are still digesting the rapid ascent of artificial intelligence, the regulatory ripple effects of quantum computing and the accelerating race for cybersecurity resilience.
Learn more

What others say…

Peloton Interactive, Inc.
John Cassels and the entire Fieldfisher team has been a valuable partner to us as we entered the European market. They are responsive and thorough, but most importantly they have really taken the time to understand our business, our goals, and our people, and the result is smart, practical advice even when we're moving fast. We think of them as an extension of our team and would happily recommend them
Legal 500
Very astute, approachable and adaptable