It is well-settled in patent law that ‘full and enabling disclosure’ is a condition precedent for the grant of patent for any invention. Any inadequacy in the disclosure is likely to result in invalidation of the patent on a challenge.
This principle was exemplified in the Supreme Court of Canada’s decision in Teva Canada Ltd. v. Pfizer Canada Inc. (2012)
Pfizer Canada’s patent claimed a broad class of compounds approved for the treatment of erectile dysfunction (“ED”). At the time Pfizer filed its patent application, it had tested and determined that the compound, Sildenafil (sold under the brand name, Viagra) was the effective compound for treating ED.
The disclosure listed four nested classes of general to particularly preferred compounds; the description contained a list of nine especially preferred compounds, which included Sildenafil. While Claim 1 of Pfizer’s patent extended to 260 quintillion different compounds, two claims (Claims 6 & 7) were directed to individual compounds alone—Claim 7 related to Sildenafil alone.
Pfizer had evidence from clinical studies that Sildenafil was the only one, in the list of nine especially preferred compounds, proven successful for treating ED. Yet, in the patent it chose to suppress that material fact; neither did it disclose that none of the other eight compounds had been tested or proven effective.
The generic drug manufacturer, Teva Canada Ltd. challenged the patent validity alleging inter alia obviousness, lack of utility and insufficient disclosure. The Federal Court of Canada, in the first instance, held the allegation unjustified. The Federal Court of Appeal, the appellate court, too upheld the verdict of the trial court.
Teva then appealed again to the Supreme Court of Canada
The main question before the court was whether the specification of the patent satisfied Section 27(3) of the Patent Act (R.S.C., 1985, c. P-4), which mandates that the specification of an invention must “fully and correctly describe the invention and its operation or use as contemplated by the inventor” such that a person skilled in the art can accomplish it.
Further, the court had to determine whether the evaluation of the sufficiency of disclosure in the patent had to be assessed by viewing each claim separately or the specification as a whole.
The recognized the "patent bargain" principle and articulated the policy rationale under the Patent Act by observing as follows:
"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…The patent bargain encourages innovation and advances science and technology."
The court further noted that Pfizer's patent application listed a vast number of potential compounds (260 quintillion), but only one—Sildenafil, the active ingredient in Viagra—was actually proven to be effective for treating erectile dysfunction. Hence, the patent used general statements, requiring any "person skilled in the art" to carry out further experimentation to determine the true invention.
The Court also concluded that Pfizer not only disclosed insufficiently, but also attempted to "game" the patenting system by claiming a broad range of compounds, while intentionally withholding specific information necessary to practice the invention.
In its unanimous verdict, the court ruled that the invention must be defined by looking at the specification as a whole—and not by viewing each patent claim as a separate invention. Pfizer's patent for the blockbuster drug Viagra was invalidated, since the company failed to meet the full disclosure requirements of the enactment. The court opined that a skilled person could not put the invention into operation without further trial.
The Pfizer patent effectively entailed a single inventive concept: the use of the effective compound for treating ED. The real invention was the use of Sildenafil, because only that compound was proven to be effective.
The Supreme Court allowed Teva's appeal, which enabled Teva Canada to immediately launch a generic version of Sildenafil in the market.
The judgment is a landmark in Canadian patent law on disclosure. The ruling affirmed the obligation of sufficient disclosure, which reflects a basic concept of patent law. The patent specifications must enable the skilled person to practice the invention without undue burden. Thus, patentees cannot make broad genus claims and rely on the skilled person to figure out which specific compound works.
Thus, the decision places onus on inventors to clearly identify the inventive component. It also reiterates that patentees cannot “game” the system by obscuring the true invention.
At Blaze Ventures, we have qualified professionals and elaborate processes for assisting enterprises and inventors ensure pharmaceutical claims meet the ‘sufficient disclosure’ standards of ‘patentability’.
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[1] 2012 SCC 60
