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Issue 06/67 | December 01, 2006
No anticipation of a patent by "inherent disclosure" in Canada

In a case closely watched on both sides of the border, the Federal Court of Canada (the trial level) has invalidated Calgon Corporation's patent for its water treatment process, on the basis of anticipation by prior public disclosure. However, in contrast with the parallel litigation in the United States, the Court stated that a patent cannot be anticipated by an "inherent disclosure," but only by an "enabling disclosure."

The patent described and claimed a method for treating the parasite Cryptosporidium ("Crypto") by irradiation with UV light at a lower-than-normal intensity. The inventors described the invention as being based on the discovery that one does not have to kill the organism, but only make it incapable of reproducing. The court based its result on prior public disclosures that drinking water been treated with UV light within the claimed range coupled with test results and other disclosures that this would likely have been effective to treat Crypto. However, one disclosure which was not enabling was "Trout Lake", in which the only disclosure was that contaminated water had been treated by UV within the claimed range but there was no disclosure at the time that this would have been effective against Crypto. In contrast, a similar disclosure was considered an anticipation by the American court.

The court compared a recent American decision involving the same patent (Wedeco UV Technologies, Inc v. Calgon Carbon Corporation U.S. Dist. LEXIS 48657), which found the patent invalid by "inherent anticipation," on the basis of only a partial record of the evidence before the Canadian court. According to this test, a patent may be "inherently" anticipated by a prior art disclosure that omits an element of the claimed invention, if the missing element is necessarily or inherently present and the missing element is the "natural result" flowing from application of the reference.

In contrast, the law in Canada is that a patent is anticipated only by a prior enabling disclosure of the invention. A prior use, even if public, would only anticipate a patent if it also disclosed sufficient information to enable others to practice the invention. It is not necessary that the prior disclosure has taught how the invention works, but it must have been such that a person following the disclosed process would have automatically infringed the patent. Perhaps the Calgon patent would have been valid if the prior disclosures had only disclosed use of the claimed UV intensity, but not that this would treat Crypto contamination: a person following such a teaching would not necessarily have used the treatment to treat Crypto, since there would not have been any teaching to do so.

The absence of an "inherent anticipation" test in Canada makes it potentially more difficult to invalidate a patent, but at the same time worthwhile to seek patent protection for an invention that might be considered anticipated in the United States.

The court noted a gap between infringement and anticipation: disclosure of prior use without disclosure of the "relevant facts" might not anticipate a patent even though the same use could infringe the patent after the patent issues. A person who had been previously treating water with the claimed method, but without making any disclosure that Crypto was being treated, could in principle infringe the patent after it issues. Canada offers a limited "safe harbor" in s. 56 of the Patent Act, but this may not cover prior users of processes.

The decision is Calgon Carbon Corporation v. North Bay (City) 2006 FC 1373.


To discuss this topic further, please feel free to contact the author Adrian Zahl (azahl@ridoutmaybee.com) at Ridout & Maybee LLP (www.ridoutmaybee.com), Toronto, Canada.

The information contained in this email is provided for informational purposes only and does not represent legal advice. Neither the APLF nor the author intends to create an attorney client relationship by providing this information to you through this message.

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