Canada: Prosecution History Estoppel now a reality? And will Australia follow suit?

Royal assent was given on 13 December 2018 to legislation changing parts of the Patents Act. On face value, the changes have the potential to introduce added uncertainty on how claims in a patent will be construed in any dispute between a patentee and an alleged infringer in Canada.

New Section 53.1 Patents Act (Canada) in part reads:

Admissible in evidence

53.1 (1) In any action or proceeding respecting a patent, a written communication, or any part of such a communication, may be admitted into evidence to rebut any representation made by the patentee in the action or proceeding as to the construction of a claim in the patent if:

(a) it is prepared in respect of:

  • the prosecution of the application for the patent,
  • a disclaimer made in respect of the patent, or
  • a request for re-examination, or a re-examination proceeding, in respect of the patent; and

(b) it is between:

  • the applicant for the patent or the patentee; and
  • the Commissioner, an officer or employee of the Patent Office or a member of a re-examination board.

In simple terms, the legislation aims to allow Courts to hold Canadian patentees bound to written (not oral) representations made to the Canadian patent office concerning the meaning of words / phrases in a patent claim, in any subsequent litigation proceedings in Canada.

Contrast this with what may be extracted from dicta by the Supreme Court of Canada in its seminal 2010 Free World Trust decision which held that claims in Canadian patents had to be construed purposively as per Catnic (House of Lords UK; Catnic Components Limited v Hill & Smith Limited [1982] RPC 183) and Improver (Court of Appeal, Lord Hoffman; Improver Corporation v Remington Consumer Products Limited, [1990] FSR 181).

Such purposive construction is to be made by the Court

  • with the mantle or through the eyes of the skilled person,
  • in the context of the patent specification itself,
  • without applying an overly meticulous verbal analysis which lawyers tend to indulge in by the very nature of their trade,
  • but equally without simplistic dictionary-based approaches,
  • and, relevantly, without recourse to extrinsic evidence, including a patentees opinion on how terms in a claim should be construed and/or understood, absent a corresponding ‘dictionary definition’ being present in the patent specification itself.

For a more detailed analysis of Canada’s Supreme Court decisions on claim construction, and subsequent case law also in the UK, see here.

The astute reader will note use of the discretionary ‘may’ in the legislation. This can be contrasted with the prescriptive ‘shall’ often found in legislation. It will be of interest to watch how the Canadian Courts apply such discretion, and how they will approach use of written materials, exchanged during prosecution of a patent application between the patent applicant and the Canadian Patent Office, in determining the meaning and scope of words and phrases present in a claim. It is not difficult to foresee situations where, on face value, submissions made by a patentee during prosecution of a patent application concerning the meaning of words or scope of sentences do not marry-up with how such words / phrases are interpreted by a skilled person having no knowledge of the prosecution history of the patent in question. Given enactment of the legislation and the clear intent of the legislature, it is the view of the writer, however, that Canadian courts will be hard pressed to disregard the prosecution history record, even if such could lead to objectively abstruse construction of the claims.

In Australia, the position appears to be a settled one, and change does not appear on the legislative horizon.

The Australian Patents Act does not contain provisions similar to those now present in the Canadian Patents Act. Nor are there legislative changes afoot to introduce similar provisions.

Section 116 of the Australian Patents Act 1990 provides a very limited tool in enabling a court to construe claim language by reference to ‘prosecution history’. Section 116 allows the Court, in interpreting a complete specification as amended, to refer to the specification without amendment. Ultimately, however, this is an exercise in comparing two specific documents without recourse to submissions made by the applicant in support of the amendment being made.

And on the case law front, Justice Nicholas of the Federal Court of Australia had the latest say on the question of prosecution history estoppel back in 2015 (Bradken Resources Pty Ltd v Lynx Engineering Consultants Pty Ltd [2015] FCA 1100). In that decision, his honour references Lord Hoffman in the English case of Kirin-Amgen Inc v Hoechst Marion Roussel Ltd [2004] UKHL 46 and earlier Australian case law Prestige Group (Australia) Pty Ltd v Dart Industries Inc [1990] FCA 281) and at [86] summarises the position in Australia:

“….the scope of the monopoly depends upon the proper construction of the claims read in the context of the specification as a whole and in light of the common general knowledge. The authorities in this country have eschewed recourse to extrinsic materials (such as correspondence between the patent applicant and the Commissioner) for the purpose of ascertaining the true scope of a claim.”

As is the case in the USA (but not Europe / UK), patent applicants and their patent attorneys should now be well advised to apply greater care in their interactions with Canadian patent office examiners lest stray or inaccurate representations made during patent prosecution about the meaning to be given to words and phrases in a patent claim (as granted) come home to roost during litigation of the Canadian patent.

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