Darren Hall is a J.D. candidate at Osgoode Hall and is taking the Patent Law course.
Addressing the question of whether a prior use will anticipate an invention if that prior use was previously unacknowledged, known as the doctrine of Inherent Anticipation, has been a struggle for Canadian courts.
A patent lacks novelty and is found to be invalid if the invention has been disclosed by a prior use that communicated information sufficient to “enable disclosure” of that invention. The appropriate standard for this determination is referenced to a person skilled in the art who does not use inventive skill, and who uses known analytical techniques available at the time. This doctrine was established in the case of Baker Petrolite Corp. v. Canwell Enviro-Industries Ltd.,  (F.C.A.), and has been further refined in the case of Apotex Inc. v. Sanofi-Synthelabo Canada Inc. , (S.C.C.).
In the British case of Merrell Dow Pharmaceuticals Inc. v. H.N. Norton & Co. Ltd.,  (H.L.), the issue to be decided was whether Merrell Dow’s patent for a metabolite was anticipated by the prior disclosure of Terfenadine (an anti-histamine) despite the fact that the presence of the metabolite was not acknowledged for several years after Terfenadine was patented. The metabolite is a substance necessarily produced in a patient’s liver upon consumption of Terfenadine. Lord Hoffmann, writing for the majority, concluded that the metabolite patent had been inherently anticipated, because the Terfenadine patent disclosed the formula for Terfenadine and the instructions to take it for its anti-histamine effect. The latter enabled the public to take Terfenadine and to produce the metabolite in their livers.
Two Noteworthy Canadian Decisions
The Merrell Dow case has been followed by the Canadian courts in the majority of cases dealing with inherent anticipation. However, in two recent decisions, the Federal Court and Federal Court of Appeal have endorsed a more restrictive approach toward the application of this doctrine.
In Lundbeck Canada Inc. v. Canada (Minister of Health),  (F.C.), one question to be decided was whether Lundbeck’s patent for Escitalopram, an anti-depressant, was anticipated by prior use and therefore invalid. Escitalopram is the biogically active constituent of Citalopram, a previously patented anti-depressant. Escitalopram was found to be a necessary biologically active constituent of Citalopram. Despite this, Justice Harrington found that the invention for Escitalopram had not been anticipated because another constituent of Citalopram, R-citalopram, had some, albeit minimal, biological effect. This prior use was held to be insufficient to enable disclosure and accordingly, the validity of the Escitalopram patent was upheld.
In Janssen-Ortho Inc. v. Novopharm Ltd.,  (F.C.A.), the obviousness of the invention for Levofloxacin, an antibiotic used for treating infections, was called into question upon discovering that Levofloxacin was necessarily biologically active constituent of a previously patented antibiotic, Ofloxacin. Justice Sharlow held that invention for Levofloxacin was not obvious because the prior preparation of Levofloxacin, did not meet a minimum standard of purity. Although this issue was not addressed under the heading of inherent anticipation, this holding signals the court’s preparedness to determine the merits of an invalidity claim on the basis of a “minimum purity” test.
In contrast with the Merrell Dow case, the courts in the Lundbeck and Janssen-Ortho cases have not found anticipation or invalidity where a prior composition or a prior process necessarily produced the patented substance. In those cases, the courts have introduced the additional requirement that the patented substance must be present in the prior composition at a minimum purity level, and that the patented substance also be the sole biologically active constituent in the prior composition.
The doctrine of anticipation has been interpreted in a narrow sense in order to avoid stifling innovation. However, it seems likely that the “minimum purity” and “sole constituent” tests may unduly restrict the application of the doctrine of inherent anticipation. If this development continues, it may potentially frustrate the purpose of the doctrine of anticipation: to prevent double patenting.
Improving the Balance between Encouraging Innovation and Avoiding Double Patenting
The American scholars Anne Brown and Mark Polyakov have addressed this issue concerning inherent anticipation in their 2004 work entitled “The Accidental and Inherent Anticipation Doctrines: Where Do We Stand and Where Are We Going?”. Brown and Polyakov propose the following test for inherent anticipation:
The first prong is concerned with whether the prior process or composition is useful in the art. If the answer to the first prong is no, then the anticipation is accidental (no anticipation); if the answer is yes, the second prong is whether the process or composition occurred under unusual conditions or occasionally. If the answer to the second prong is no, then the anticipation is inherent; if the answer to the second prong is yes, the anticipation is accidental (no anticipation).
This analysis resets the focus on the central question of the inherent anticipation doctrine: whether the prior process or composition actually produced the patented substance reliably and to a point of certainty, and achieved a useful result in the art.
Brown and Polyakov’s test appropriately upholds the validity of novel inventions by rejecting prior processes and compositions that are not reliably reproduced and are not useful in the art. Conversely, the test appropriately finds anticipation in situations where a prior process or composition was reliably produced and was useful in the art.
For the above reasons, it seems that the test proposed by Brown and Polyakov strikes an appropriate balance between the competing policy interests of encouraging innovation and of minimizing the risks associated with granting patents that are not novel, such as double patenting. By adopting Brown and Polyakov’s framework in their analyses, Canadian courts may improve the balance between these competing policy interests.