David A. Ruston

David is a partner at Sim & McBurney where he manages large international IP portfolios for domestic clients, which includes drafting, filing and prosecuting patent applications worldwide, and managing Canadian portfolios for large and medium-sized foreign companies. David prepares patentability, freedom-to-operate and validity opinions, performs due diligence in commercial transactions involving IP assets, and provides technical support in litigation matters.

David has appeared before the Patent Appeals Board of the Canadian Intellectual Property Office (CIPO) on numerous occasions, boasting a high success rate, and is one of the few Canadian practitioners to have successfully concluded a patent abuse application before CIPO and obtained a compulsory license of third-party patent rights for a domestic client.

David graduated from Queen’s University in Kingston, Ontario in 1986 with a B.Sc. in electrical engineering. Following graduation, he began specializing in patent agency matters, focusing on electronics, computer and information technology. He qualified as a Registered Patent Agent in Canada in 1988, received his professional engineer designation in the province of Ontario in 1989 and became a Registered Patent Agent in the United States in 1990.

In his spare time, David is active in sports, the community and the arts. He can be found on the golf course, squash court, curling or enjoying time with family and friends. David is a patron of Squash Ontario, the Royal Ontario Museum, the Canadian Opera Company and Toronto East General Hospital. David also sits on the Board of Governors for Junior Achievement of Central Ontario (JACO).


Contact Information

T. 416-849-8390 E. F. 416-595-1163


Registered Patent Agent, Canada (1988)
Registered Professional Engineer, Province Of Ontario (1989)
Registered Patent Agent, United States (1990)


B.Sc., Electrical Engineering, Queen’s University (1986)

Professional Associations

Fellow, Intellectual Property Institute of Canada
Institute of Electrical and Electronic Engineers
Canadian Society of Electrical and Computer Engineers