Daniel is a Chartered (UK) and European Patent Attorney whose broad background in Mechanical Engineering allows him to work across a range of technologies spanning the energy, automotive, consumer device and medical technologies. Daniel has particular expertise in downhole technologies, product handling systems, electronic cigarettes and medical devices.

Daniel’s practice focuses on handling complex matters for his clients, including due diligence and freedom-to-operate projects, where he is recommended by his clients for providing commercial and pragmatic advice.  He has experience managing significant due diligence and product mapping exercises to support technology acquisition, and he has extensive expertise in planning and managing freedom to operate projects for complex technologies.  Daniel often comes up with innovative approaches to delivering commercial advice to his clients.  He understands the wider context in which IP sits and tailors the strategy to projects to ensure advice is aligned with broader objectives and the big picture.

Daniel regularly advocates for his clients before the EPO Opposition Divisions and Boards of Appeal and has a strong track record of achieving excellent results.  Daniel is comfortable handling high value, multi-party proceedings, for example working closely with a litigation team to align the approach before the EPO with wider commercial concerns and litigation strategies.  Daniel is commended for his ability to identify the key issues and achieve good results at hearings.  Daniel has also managed and advocated on a case referred to the EPO’s Enlarged Board of Appeal. 

In addition to contentious work, Daniel regularly drafts and prosecutes applications before the UKIPO and EPO.  He builds and manages international patent portfolios for his clients and enjoys advising on filing and prosecution strategy to maximise the portfolio effectiveness.  He also advises on registered designs.  Daniel has experience working in house for a large energy company on secondment.

Daniel is a registered UPC representative.  Daniel earned a degree and Master’s in Mechanical Engineering from the University of Cambridge.

“Daniel Sizer is a pleasure to work with. He is eager, detail-oriented and has a commercially pragmatic approach to the client's tasks at hand.” – Legal 500, 2025