The Federal Court of Appeal has held that an issued Canadian patent cannot be invalidated on the ground that the applicant failed to respond in good faith to a requisition from the Patent Office made during the prosecution of the application.  In Weatherford Canada Ltd. v. Corlac Inc., 2011 FCA 228, dated July 18, 2011, the Court of Appeal held that the operation of section 73 of the Patent Act is extinguished once the patent issues.  To the extent that decisions of the Federal Court have suggested otherwise, the Court of Appeal held that “they should not be followed.”  In the Court’s analysis, it is subsection 53(1), rather than section 73(1), which governs misrepresentations in relation to issued patents.

In Weatherford, the defendants in an action for patent infringement had alleged that the patent was invalid because the applicant had failed to respond in good faith to a requisition made by the Patent Office during the prosecution of the application.  The defendants relied on section 73 of the Patent Act, which provides in part:

 73. (1) An application for a patent in Canada shall be deemed to be abandoned if the applicant does not

(a) reply in good faith to any requisition made by an examiner in connection with an examination, within six months after the requisition is made or within any shorter period established by the Commissioner;       

The Federal Court rejected this attack on legal and factual grounds.  The Court of Appeal affirmed, holding that section 73 is not directed to the validity of a patent once it issues.  The Federal Court of Appeal’s decision in Weatherford seeks to provide clarification on the state of Canadian law, which recent decisions of the Federal Court had suggested might allow a Canadian patent to be invalidated for lack of good faith prosecution.  In Weatherford, the Federal Court of Appeal reaffirmed the long-held view that there is “no provision in the Patent Act that an untrue allegation, even amounting to a misrepresentation, made in the course of the prosecution of the application for the patent in the Canadian Patent Office has any effect on the validity of the patent.”  Lovell Manufacturing Co. v. Beatty Brothers Ltd. (1962), 41 C.P.R. 18 at p. 40 (Ex. Ct.).

Although the Court in Weatherford  refused to expand the scope of section 73, Canadian patent applicants are reminded of their obligation to act in good faith in their ex parte dealings with the Patent Office.  As the Federal Court of Appeal noted in Weatherford, a Canadian patent will be void pursuant to section 53 of the Act “if any material allegation in the petition of the applicant in respect of the patent is untrue, or if the specification and drawings contain more or less than is necessary for obtaining the end for which they purport to be made, and the omission or addition is wilfully made for the purpose of misleading.”  It remains Canadian law that an inventor “must act uberrima fide and give all information known to him that will enable the invention to be carried out to its best effect as contemplated by him.”  Noranda Mines Ltd. v. Minerals Separation North American Corp. (1947), 12 C.P.R. 99 at pp. 111-12 (Ex. Ct.).