Teva Canada Ltd. v. Pfizer Canada Inc., 2012 SCC 60

Summary – According to the highest court in Canada, a patent containing, inter alia, two separate claims, each directed to the new use of a specific compound, does not satisfy the statutory disclosure requirements if the patent only says “a compound” works for the claimed use, but does not actually identify which of the two compounds works.  It is improper to require the skilled reader to conduct “a minor research project” to determine the invention (para. 74).  Pfizer’s Canadian Patent No. 2,163,446 (the “`446 Patent”) contains a specific claim to the use of sildenafil (the active compound in Viagra) for the treatment of erectile dysfunction (“ED”).  In a unanimous decision written by Justice LeBel, the Supreme Court of Canada (“SCC”) determined that the `446 Patent did not meet the disclosure requirements of subsection 27(3) of the Patent Act (“Act”) because it did not disclose that the compound that works was sildenafil or that the other claimed compounds had been found not to be effective in treating ED.

Analysis – The `446 Patent relates to the use of a “compound of formula (I)” or a “salt thereof” as a medicament for the treatment of ED.  The `446 Patent ends with seven cascading claims for successively smaller ranges of compounds, with Claims 6 and 7 relating to a single compound each.  Only sildenafil, the subject of Claim 7, had been shown to be effective in treating ED as of the filing date of the `446 Patent.  The ‘446 Patent states:

“In man, certain especially preferred compounds have been tested orally in both single dose and multiple dose volunteer studies. Moreover, patient studies conducted thus far have confirmed that one of the especially preferred compounds induces penile erection in impotent males.”

Teva applied for a Notice of Compliance (“NOC”) in order to produce a generic version of Viagra.  In a proceeding arising under the Patented Medicines (NOC) Regulations, the Federal Court prohibited the Minister of Health from issuing the requested NOC and the Federal Court of Appeal dismissed the appeal.  The main issue before the SCC was whether the `446 Patent met the disclosure requirements under subsection 27(3) of the Act, which requires, among other things, that the specification “correctly and fully describe the invention”.

The first step for the SCC was to define the nature of the invention in the `446 Patent.  The SCC disagreed with the lower courts’ interpretation of Boehringer[1] standing for the broad proposition that in every case, each claim in a patent application concerns a separate invention.  In particular, the SCC stated that the Exchequer Court in Boehringer reached the conclusion that each claim in the patent in question concerned a separate invention only after considering the specification as a whole.  After considering the specification of the `446 Patent as a whole, the SCC found nothing to support the view that the use of sildenafil for the treatment of ED was a separate invention from the use of any of the other many claimed compounds for that same purpose.  There are no specific attributes or characteristics ascribed to sildenafil in the ‘446 Patent disclosure that would set it apart from the other compounds.

Arguably, there are a few factors which make this SCC finding unusual:

  • sildenafil was identified in the `446 Patent as an “especially preferred compound”;
  • the `446 Patent included the statement that “one of the especially preferred compounds induces penile erection in impotent males”; and
  • the `446 Patent contained a specific claim to the use of sildenafil to treat ED.

The SCC found that there was still nothing that distinguished sildenafil from the other eight “especially preferred compounds”.  As such, the SCC determined that the use of sildenafil and the other compounds for the treatment of ED comprised a single inventive concept.

The second step for the SCC was to determine whether the disclosure in the `446 Patent was sufficient.  In this case, Pfizer had conducted tests that demonstrated that sildenafil was effective in treating ED (without specifically identifying sildenafil as the effective compound in the disclosure of the `446 Patent).  However, none of the other compounds in the `446 Patent had been shown to be effective in doing so.  As such, the SCC concluded that the invention in the `446 Patent was the use of sildenafil for the treatment of ED and held that this had to be disclosed in order to meet the disclosure requirements set out in subsection 27(3) of the Act.  The SCC disagreed with the lower courts’ interpretation of Consolboard[2] standing for the proposition that the only relevant questions that must be answered under the statutory disclosure requirements are:  “What is your invention?” and “How does it work?”  The SCC stated that Consolboard makes it clear that the specification, which includes the claims and the disclosure, must define the “precise and exact extent” of the privilege being claimed so as to ensure that the public can, having only the specification, make the same use of the invention as the inventor.

In its sufficiency analysis, the SCC found that the disclosure in the specification of the `446 Patent would not have enabled the public “to make the same successful use of the invention as the inventor could at the time of his application” [emphasis added] because it did not indicate that sildenafil was the effective compound.  Even if a skilled reader could have narrowed the effective compound down to the specific two chemicals of Claim 6 and Claim 7, further testing, amounting to that of a “minor research project”, would have been required to determine which compound was the true invention.  In fact, Pfizer’s own expert witness admitted that a person skilled in the art who read the `446 Patent would not know which compound was shown to be useful in treating ED.

The SCC went on to say that “Pfizer had the information needed to disclose the useful compound and chose not to release it” and that “[i]t chose a method of drafting that failed to clearly set out what the invention was.” (para. 76)  In commenting on the common practice of cascading claim drafting (broad genus claims narrowing progressively to specific species claims), the SCC stated that such a practice does not necessarily interfere in every case with the public’s right to disclosure and that the skilled reader knows that, when a patent contains cascading claims, the practically useful claim will usually be the one at the end concerning an individual compound.  The apparent problem in this case however, was that “the claims ended with two individually claimed compounds, thereby obscuring the true invention” and denying the public’s right to proper disclosure.  According to the SCC:

“…Pfizer gained a benefit from the Act – exclusive monopoly rights – while withholding disclosure in spite of its disclosure obligations under the Act.  As a matter of policy and sound statutory interpretation, patentees cannot be allowed to ‘game’ the system in this way.” (para. 80)

Teva also argued invalidity of Claim 7 of the `446 Patent on the basis of insufficient disclosure of the sound prediction of utility.  The SCC rejected this argument on the basis that sildenafil’s utility had actually been demonstrated by Study 350 (which was merely referred to in the `446 Patent but the data of which was not disclosed therein), as of the time of filing.  This “takes the invention out of the realm of sound prediction”. (para. 42).

Practice Point - 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.  If there is no quid – proper disclosure – then there can be no quo – exclusive monopoly rights.  This much anticipated decision from the SCC provides a warning to patentees on the need to make full disclosure of their inventions.  Careful use of language in the disclosure could have saved the ‘446 Patent.  Patentees will need to temper the technical/somewhat formulistic requirements of patent drafting with the standard business concerns that one’s patents do not simply “tell all”.  The challenge is to simply tell enough.  Arguably the SCC has somewhat changed the approach to these classic patent drafting issues.

There is question as to whether this decision will be limited to the peculiar facts of this case or will have a broader impact.  For example:

  1. How will this decision be applied to product claims given that the claims of the `446 Patent in question were use claims?
  2. Would the outcome have been different if the claims of the `446 Patent had ended with only one individually claimed compound, namely sildenafil, rather than two?
  3. How does this decision fit with the long time understanding that section 80(1)(f) of the Patent Rules, although requiring that there be set forth at least one mode contemplated by the inventor for carrying out the invention, does not appear to require the applicant to identify which of several modes, if several are provided in the application, is “the” best mode?
  4. As a result of this decision, Teva has received an NOC for its generic version of Viagra and is already on the Canadian market.  Likewise, four other generic companies, including Cobalt, Pharmascience, Sandoz and Mylan have also received their NOCs.    This decision was in respect of a proceeding that arose under the Patented Medicines (NOC) Regulations.  It will be interesting to see:  (1) whether Pfizer will sue Teva or any other generics (once on the market) in a patent infringement action and (2) how this decision will affect Apotex’s patent validity action which is to be heard starting November 26, 2012.