The Perplexities of Patent Prosecution History: Procedure over Principle?

12 Pages Posted: 20 Apr 2021

See all articles by David Vaver

David Vaver

York University - Osgoode Hall Law School

Date Written: April 2021


What is it about patent legislation? Speaking for the Supreme Court in 1981, Justice Dickson, later Chief Justice, said of the disclosure provision in the Patent Act (now subsection 27(3)) that:

"[i]t gives the impression of a mélange of ideas gathered at random rather than an attempt to enunciate, clearly and concisely, a governing principle or principles. This is perhaps understandable in that the section is the product of amendment over a period of many years. The language simply does not lend itself to a tight, literal interpretation. It is, and should be treated as, a parliamentary pronouncement, in general terms."

Nearly 40 years later nothing much seems to have changed. Take the new section 53.1 of the Patent Act that took effect in 2019. It was not the product of amendment over many years, nor did it present a random mélange of ideas. It had only one idea. That was to reverse a 2000 decision of the Supreme Court in Free World Trust v Electro Santé Inc and allow what transpires in the Patent Office (“PO”) during the processing of a patent application — its “prosecution history” — potentially to affect the scope of the patent eventually granted. Subsection 53.1(1) could have simply said that: i.e., a patent’s prosecution history is relevant and admissible to aid in the construction of a patent claim or specification. Instead its drafting suffers from the malady highlighted by Justice Dickson. Its governing principles are not clearly and concisely stated. They seem rather to be “secreted in the interstices of procedure.” To give the section “a tight, literal interpretation,” as some courts have already done, therefore seems inappropriate. That approach runs counter to the Interpretation Act’s direction that all statutory provisions are “deemed remedial” and so require “such fair, large and liberal construction and interpretation as best ensures the attainment of [their] objects.” Patent legislation is not immune from these strictures. An ineptly drafted provision may indeed sometimes need to be treated the way Justice Dickson treated subsection 27(3), as “a parliamentary pronouncement, in general terms.”

Suggested Citation

Vaver, David, The Perplexities of Patent Prosecution History: Procedure over Principle? (April 2021). Osgoode Legal Studies Research Paper, Available at SSRN: or

David Vaver (Contact Author)

York University - Osgoode Hall Law School ( email )

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Toronto, Ontario M3J 1P3

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