IP Compendium

Notes on Canadian intellectual property law

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Sufficiency of Disclosure

The sufficiency (or insufficiency) of disclosure in a patent specification is an independent ground for invalidity apart from anticipation, obviousness, and inutility. In short, an attack of insufficiency alleges that the patent specification does not actually teach the person of ordinary skill in the art how to practice the invention - the patentee has failed to give sufficient consideration for his or her patent, therefore the patent grant was void.

Statutory basis

S. 27(3) of the the Patent Act1 sets out the statutory basis for an insufficiency attack. It provides the requirements that a patent specification must meet:

27. (3) The specification of an invention must

(a) correctly and fully describe the invention and its operation or use as contemplated by the inventor;

(b) set out clearly the various steps in a process, or the method of constructing, making, compounding or using a machine, manufacture or composition of matter, in such full, clear, concise and exact terms as to enable any person skilled in the art or science to which it pertains, or with which it is most closely connected, to make, construct, compound or use it;

(c) in the case of a machine, explain the principle of the machine and the best mode in which the inventor has contemplated the application of that principle; and

(d) in the case of a process, explain the necessary sequence, if any, of the various steps, so as to distinguish the invention from other inventions.


S. 27 of the Patent Act has been said to lie “at the heart of the whole patent system”.2 According to the bargain theory of patent law, an inventor can only obtain a monopoly on his invention if they fully disclose the invention. In Pfizer Canada Inc v Teva Canda Ltd (Sildenafil),3 the Supreme Court wrote of this theory:

The patent system is based on a “bargain”, or quid pro quo: the inventor is granted exclusive rights in a new and useful invention for a limited period in exchange for disclosure of the invention so that society can benefit from this knowledge. This is the basic policy rationale underlying the Act. The patent bargain encourages innovation and advances science and technology.4

The quid pro quo was described in no uncertain terms by Binnie J. in Apotex Inc v Wellcome Foundation Ltd (AZT):5

A patent, as has been said many times, is not intended as an accolade or civic award for ingenuity. It is a method by which inventive solutions to practical problems are coaxed into the public domain by the promise of a limited monopoly for a limited time. Disclosure is the quid pro quo for valuable proprietary rights to exclusivity which are entirely the statutory creature of the Patent Act . Monopolies are associated in the public mind with higher prices. The public should not be expected to pay an elevated price in exchange for speculation, or for the statement of “any mere scientific principle or abstract theorem” (s. 27(3) ), or for the “discovery” of things that already exist, or are obvious. The patent monopoly should be purchased with the hard coinage of new, ingenious, useful and unobvious disclosures.6

A patent specification that fails to disclose what the invention is or how it works provides no benefit to the public. Since the inventor did not pay the “hard coinage” of the disclosure, the patent is void.

Despite the strongly worded statements from the Supreme Court, and the centrality that has been ascribed to this doctrine, lower courts have repeatedly cautioned that an attack for insufficiency of disclosure is a “technical attack” that ought not to defeat a meritorious invention.7 This note of caution may be a necessity given that the consequences of an insufficient disclosure are severe. A court must therefore look carefully at the specification and determine whether, from the perspective of a person of ordinary skill in the art armed with Common General Knowledge, the invention as described can be put to practice.8

What must be disclosed

A patent specification must sufficiently describe an invention so as to enable a skilled person to put the invention to work. The following passage by Dickson J. in Consolboard Inc v MacMillan Bloedel (Sask) Ltd9 has been repeatedly cited as the leading statement of the law:

Section 36(1) seeks an answer to the questions: “What is your invention? How does it work?” With respect to each question the description must be correct and full in order that, as Thorson P. said in Minerals Separation North American Corporation v. Noranda Mines, Limited10:

… when the period of monopoly has expired the public will be able, having only the specification, to make the same successful use of the invention as the inventor could at the time of his application. [at p. 316]

We must look to the whole of the disclosure and the claims to ascertain the nature of the invention and methods of its performance, (Noranda Mines Limited v. Minerals Separation North American Corporation11), being neither benevolent nor harsh, but rather seeking a construction which is reasonable and fair to both patentee and public. There is no occasion for being too astute or technical in the matter of objections to either title or specification for, as Duff C.J.C. said, giving the judgment of the Court in Western Electric Company, Incorporated, and Northern Electric Company v. Baldwin International Radio of Canada12, at p. 574, “where the language of the specification, upon a reasonable view of it, can be so read as to afford the inventor protection for that which he has actually in good faith invented, the court, as a rule, will endeavour to give effect to that construction”. Sir George Jessel spoke to like effect at a much earlier date in Hinks & Son v. Safety Lighting Company13. He said the patent should be approached “with a judicial anxiety to support a really useful invention”.

In light of the foregoing I turn again to the judgment of the Federal Court of Appeal. With great respect, in my opinion that Court erred in two fundamental respects in overturning the judgment of Collier J. The Court reversed, as I understand the judgment, for the reason that the applicant had not made distinctly clear (1) to the public (2) the utility of the invention. In his reasons for judgment, Chief Justice Jackett stated in a passage which I repeat for ease of reference:

In our view, having regard to the obvious object of section 36 of making “patent” to the public (as a consideration for the monopoly) all aspects of the invention (in the sense defined by section 2 of the Patent Act) and particularly its utility, there is no compliance with that section unless the applicant in his specification distinctly claims the “part, improvement or combination which he claims” having “correctly and fully” described, inter alia, its utility. [The underlining is my own.]

In my view it is a well established principle that a patent specification is addressed, not to the public generally, but to persons skilled in the particular art. I am further of the opinion that s. 36(1) does not impose upon a patentee the obligation of establishing the utility of the invention.14

1 Patent Act, RSC 1985, c P-4.
2 Consolboard Inc v MacMillan Bloedel (Sask) Ltd, [1981] 1 SCR 504 at 517, referring to what was then s. 36 of the Patent Act.
3 2012 SCC 60.
4 Ibid at para 32.
5 2002 SCC 77
6 Ibid at para 37.
7 Airseal Controls Inc v M & I Heat Transfer Products Ltd (1993), 53 CPR (3d) 259 at 274 (FCTD), aff'd (1997) 77 CPR (3d) 126 (FCA), citing Burton Parsons Chemicals Inc v Hewlett-Packard (Canada) Ltd, [1976] 1 SCR 555, 17 CPR (2d) 97 at 104; AB Hassle v Genpharm Inc, 2003 FC 1443 at para 76, aff'd 2004 FCA 413, leave to appeal refused [2005] SCCA No 10. See also Roger T Hughes & Dino P Clarizio, Hughes & Woodley on Patents, 2d ed, looseleaf (Markham: LexisNexis, 2005) at §34.
8 Hughes, ibid.
9 [1981] 1 SCR 504.
10 [1947] Ex CR 306.
11 [1950] SCR 36.
12 [1934] SCR 570.
13 (1876), 4 Ch D 607.
14 Consolboard at 520-521.
patents/disclosure.txt · Last modified: 2015/08/11 11:42 by KPS