In a recent unanimous decision by the Supreme Court of Canada
(Teva Canada Limited v Pfizer Canada
Inc.), Pfizer Canada's patent to its multi-million
dollar selling Viagra was invalidated for insufficient disclosure.
The decision allows Teva and others to market generic versions of
Viagra® well before the patent's 2014 expiry.
While these are costly consequences for the pharma giant, the
case highlights an important lesson regarding patent utility and
disclosure requirements in Canada.
Canadian Patent No. 2,163,446 disclosed and claimed the use of
sildenafil, the active component of the hugely successful Viagra,
for the treatment of erectile dysfunction. Sildenafil was
previously known and initially developed by Pfizer for treatment of
hypertension and angina.
Claim 1 of the '446 patent covered a staggering 260
quintillion possible compounds, gradually narrowing to claim 6
covering one compound and claim 7 covering sildenafil. While the
specification suggested that "one of the especially preferred
compounds induces penile erection in impotent males", it fell
silent on the fact that that compound was in fact sildenafil.
At the Federal Court and Federal Court of Appeal levels, Pfizer
was successful in arguing that in light of Section 58 of the
Patent Act, possible invalidity of broad claims 1 to 5
should not affect claim 7, thereby maintaining patent protection
for use of sildenafil. The FCA also applied the questions a)
"What is the invention?" and b) "How does it
work?" to assess sufficiency of disclosure, and found that
both requirements were met by Claim 7.
These decisions were unanimously overruled by the Supreme Court.
The SCC rejected the claim-by-claim approach to validity analysis,
stating instead that validity of the invention as a whole must be
assessed. If the patent does not sufficiently disclose the
invention, then the patent as a whole is invalid, not merely some
of the claims.
The SCC further held that the relevant test for sufficient
disclosure was not a simple two-question test, but rather whether a
skilled person could, using only the information contained in the
specification, produce the invention described therein.
In the case of '466 patent, a skilled person would be unable
to determine if the compound of claim 6 or claim 7 was the
effective compound without extensive experimentation. The patent
failed to enable the "public to make the same successful use
of the invention as the inventor could at the time of the
application", and was consequently found void.
SCC stated: "Pfizer gained benefit under the Act -
exclusive monopoly rights - while withholding disclosure in spite
of its disclosure obligations. As a matter of policy and sound
statutory interpretation, patentees cannot be allowed to
"game" the system this way."
The case originated under the Patented Medicines (Notice of
Compliance) Regulations and the Supreme Court had the option
of merely allowing the Minister of Health to issue a Notice of
Compliance to Teva. Instead, the SCC chose to rule the patent void.
Presently Pfizer is challenging the ruling on the basis that the
Supreme Court did not have jurisdiction to invalidate the patent,
only to determine the question of the Notice of Compliance.
Whatever the outcome of Pfizer's challenge, the decision
emphasizes the importance of providing full and sufficient
disclosure an invention in a patent. When it comes to the
"heart of the patent bargain", that is public disclosure
in exchange for limited monopoly, one cannot have one's cake
and eat it too.
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guide to the subject matter. Specialist advice should be sought
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A recent Saskatchewan Court of Queen's Bench decision allowed a court-appointed receiver to sell and transfer intellectual property rights free and clear of encumbrances, finding that a license to use improvements of an invention was a contractual interest and not a property interest.
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