Partner, Patent Attorney London
Profile of Simon O'Brien

I joined D Young & Co in 2001 and became a partner in 2010. It’s a pleasure to work in a team of talented and diverse legal professionals. From out-of-the-box creative thinking to deep commercial insight, we pool our skills to give our clients the best possible chance of success.

My area of expertise encompasses both biological and chemical subject matter including the fields of molecular biology, biotechnology, biochemistry, food technology and nutrition, plant physiology, diagnostics, pharmaceuticals and polymer chemistry. My client list is broad, ranging from blue chip companies to many large and small clients from Europe, the United States and Japan.

I handle worldwide patent portfolios and advise on all aspects of patent law including patent drafting and prosecution, due diligence, and the provision of validity and infringement opinions. I have considerable experience in contentious inter partes proceedings before the EPO and I regularly represent clients in EPO oppositions. I also advise clients completing IP due diligence for stock market flotations.

I have chaired and lectured at numerous international conferences and conventions on life science issues in the patent arena.

I also launched and regularly host D Young & Co's 'Biotechnology European Patent Case Law' webinars. If you are interested in signing up to attend future webinars, please email


Recognised as a recommended individual by IAM Patent 1000 2024.


  • MA in Natural Sciences, Churchill College, University of Cambridge.
  • PhD in Biological Chemistry and Genetics, University of Cambridge.
  • Research into mode of action and biosynthesis of vancomycin group antibiotics, funded by Eli Lilly.
  • Certificate in Intellectual Property Law, Queen Mary, University of London.
  • European Patent Attorney 2007.
  • Chartered Patent Attorney 2006.
  • Registered representative before the Unified Patent Court (UPC), 2024.


  • Chartered Institute of Patent Attorneys (CIPA).
  • European Patent Institute (epi).


  • Contributor to CIPA’s European Patents Handbook.
  • Are Genes Patentable? Simon O'Brien and David Gass, Financier World September 2011.
  • Kinetic barriers and ordering of non-covalently bound states. O’Brien, S. W.; Shiozawa, H.; Zerella, R.; O’Brien, D. P.; Williams, D. H.; Org Biomol. Chem. 2003 Feb 7;1(3):472-7.
I believe that the quality of support provided by Simon and Matthew have really contributed to create value for our IP.
Legal 500
Catherine Mallalieu and Simon O’ Brien are very reliable and have excellent legal and scientific backgrounds.
O'Brien is a collaboratively minded and commercially savvy practitioner who always delivers bespoke advice.
IAM Patent 1000
Simon O’Brien’s EPO contentious experience means that he can turn a weak biochemical patent into an unimpeachable one before the examiners.
IAM Patent 1000
Highly recommended.
Legal 500
Acclaimed in the life sciences is Simon O’Brien, who blends “comprehensive knowledge of scientific matters” with “the ability to mesh patent prosecution strategy with technological developments”.
IAM Patent 1000
Matthew Caines and Simon O’Brien...are top-level patent attorneys, as they have exhaustive knowledge in life science technologies, considerable experience and provide support for patentability analyses, define prosecution strategies and evaluate infringement matters.
Legal 500
Experienced European patent attorney.
IP Stars (Managing IP)
O’Brien has the technical expertise and experience to handle even the most delicate and vital matters in a tight timeframe.
IAM Patent 1000
Simon O’Brien has significant expertise in working with venture capital companies on biological and chemical-related mandates.
Legal 500
Experienced senior European patent attorney.
IP Stars (Managing IP)
Simon O’Brien is a pleasure to work with.
IAM Patent 1000
Technically proficient, with a PhD in biological chemistry, Simon O’Brien has also cultivated significant commercial savvy and regularly provides players across the life sciences industry with IP due diligence in advance of stock market flotations.
IAM Patent 1000
Biotechnology specialist Simon O'Brien is appreciated by his clients: "He has achieved our desired goals on every matter we have entrusted to him", says one.
IP Stars (Managing IP)
The globally minded Simon O'Brien is well versed in both biology and chemistry.
IAM Patent 1000
Simon O'Brien secures plaudits for this "notable activity on the life sciences side" and wealth of experience handling patent prosecutions, validity and infringement matters.
Who's Who Legal
He seamlessly anticipates clients’ needs and consistently meets tight deadlines.
IAM Patent 1000