A recent decision of the Federal Court, GlaxoSmithKline v. Apotex, confirms that, even under the post-1989 provisions of the Patent Act (the "Act"), patents that issue from voluntary divisional applications are susceptible to attacks of invalidity on the ground of double patenting. The prohibition against double patenting is one of the numerous grounds for invalidating Canadian patents. In Whirlpool v. Camco, the Supreme Court of Canada held that the prohibition against double patenting involves two branches, namely "same invention" double patenting and "obviousness" double patenting. Under the "same invention" branch, a second patent is invalid if its claims are "identical or coterminous" with those of a patent that issued earlier. Under the "obviousness" branch, a second patent is invalid if its claims are not "patentably distinct" (i.e., novel and inventive) from those of an earlier patent. The courts (including the Supreme Court) have used language in some cases that suggests that a finding that a second patent displays either novelty or inventive ingenuity over the first patent is sufficient to rebut an attack of double patenting. It is more likely, however, that both novelty and inventive ingenuity are required to support a second patent.
The courts have used two rationales to justify the prohibition against double patenting, namely that 1) one invention may be the subject of only one patent, and 2) permitting multiple patents for one invention results in an improper extension of the patent monopoly. In Whirlpool, the rationale for the prohibition was stated to be that the Act provides that an "inventor is only entitled to "a" patent for each invention. If a subsequent patent issues with identical claims, there is an improper extension of the monopoly."
Pursuant to section 36 of the Act, where an application describes more than one invention, the applicant may voluntarily limit the application to one invention and file one or more divisional application(s) that claim any other invention(s) disclosed. However, on the direction of the Commissioner of Patents, the applicant shall file such divisional application(s).
It is settled law that the prohibition against double patenting does not apply to patents resulting from divisional applications directed by the Commissioner. However, the prohibition has been applied against patents that issued from voluntary divisional applications under the pre-1989 provisions of the Act. Until recently, there was some uncertainty as to whether the prohibition was applicable to patents that issue from divisional applications under the post-1989 provisions of the Act.
Under the pre-1989 provisions of the Act, the term of a patent grant is 17 years from the date of grant. Thus, where a second patent issues for the same invention as, or for an invention that is not patentably distinct from, that claimed in an earlier patent, there would be an improper extension of the monopoly to that invention.
Under the post-1989 provisions, the term of a patent grant is 20 years from the date of filing. Since a divisional application shares the same filing date as the original application, the patent that issues from a divisional application does not extend the monopoly granted to the patent that issued from the original application.
In GlaxoSmithKline, GlaxoSmithKline argued that, under the post-1989 provisions, a patent that issued from a divisional application cannot be found invalid on the ground of double patenting. Counsel submitted that "the sin of double patenting" had been removed by the 1989 amendments, since patents that issue from divisional applications under the post-1989 provisions do not extend the patent term accorded to the invention. The Federal Court disagreed and stated that GlaxoSmithKline had overlooked the particular impact that multiple patents can have under the Patented Medicines (Notice of Compliance) Regulations, which enable a patentee of a medicine to obtain an injunction to prevent regulatory approval of a generic equivalent. Further, and more importantly from the perspective of general patent law, the court held that a patentee should not be able to receive additional patents for the same invention. Even though there is no extension of the monopoly to the invention, inventive ingenuity is still required to support the second patent.
The message to be taken from this decision is that the filing and prosecution of divisional applications in Canada, including the cancellation of claims in a parent or other divisional application, requires a careful strategic analysis. Risks may be less in the case of division required by the Patent Office than where division is voluntary. However, in all cases, careful attention should be given to consideration of the merits and disadvantage of filing a divisional application and the timing of such applications.
The content of this article is intended to provide a general guide to the subject matter. Specialist advice should be sought about your specific circumstances.