2,410,201 – ACLASTA – zolendronate
In a four paragraph decision in Cobalt / zolendronate, the FCA has affirmed Hughes J’s decision that Novartis’s ‘201 patent is invalid for claiming methods of medical treatment. The patentability of methods of medical treatment is a difficult area of Canadian law. There are two questions: Are methods of medical treatment patentable? What is a method of medical treatment? The answer to the first question is a clear "no," at least at the FCA level, but the answer to the second question remains obscure, with the result that we know that methods of medical treatment are unpatentable, but we don’t know how to tell whether or not a claimed invention is a method of medical treatment.
On the first question, the FCA has consistently held that methods of medical treatment are not patentable, relying, as in this case , on the SCC decision in Tennessee Eastman  SCR 111. When Tennessee Eastman was decided, s 41 of the Act (now repealed) provided that substances intended for medicine could not be patented as such, but only in a product-by-process claim. As the SCC explained, this directly implies that a method of medical treatment consisting of using a compound to treat a disease cannot be claimed, or s 41 could be circumvented by claiming that method using the compound “however prepared” (177). But the SCC decision did not turn solely on the need to prevent an end-run around s 41. The decision also suggests that methods of medical treatment are unpatentable as not being within the definition of “invention.” However, the SCC’s reasoning on this point was extremely cursory. After noting that medicinal compounds and processes for making them were clearly “invention[s]”, the Court said:
But what of the method of medical or surgical treatment using the new substance? Can it too be claimed as an invention? In order to establish the utility of the substance this has to be defined to a certain extent. In the case of a drug, the desirable effects must be ascertained as well as the undesirable side effects. The proper doses have to be found as well as methods of administration and any counter-indications. May these therapeutic data be claimed in themselves as a separate invention consisting in a method of treatment embodying the use of the new drug? I do not think so, and it appears to me that s.41 definitely indicates that it is not so.
Text, context and purpose must all be considered in interpreting a statute. As I read Tennessee Eastman, the SCC is saying that s 41 is an important part of the context for interpreting “invention” which led it to conclude that methods of medical treatment did not fall within that definition.
The problem is that s 41 was subsequently repealed: what does this mean for the interpretation of “invention”? Should we say that methods of medical treatment are excluded on the basis of “I do not think so,”; or should we say that just as s 41 implied that “invention” does not include methods of medical treatment, so the repeal of s 41 implies a corresponding amendment to the definition of “invention”? This question has no easy answer. The SCC subsequently addressed Tennessee Eastman in Wellcome / AZT 2002 SCC 77,  saying
Tennessee Eastman was concerned with the patentability of a surgical method for joining incisions or wounds by applying certain compounds. The decision was based on the former s. 41 of the Patent Act, now repealed. The Court concluded that the method (apart from the compounds) was not patentable. The policy rationale, as explained by Wilson J. in Shell Oil, supra, at p. 554, was that the unpatentable claim was
essentially non-economic and unrelated to trade, industry, or commerce. It was related rather to the area of professional skills.
The statement that “The decision was based on the former s. 41 of the Patent Act, now repealed,” implies that Tennessee Eastman really turned on s 41, which would imply that the definition of "invention" may have changed. But the statement regarding the policy rationale is much broader, and does not turn on s 41 at all, which would imply that the definition has not changed. And the notion that methods of medical treatment are “essentially non-economic” is a meaningless fiction, as the HCA authoritatively explained in its recent decision in Apotex v Sanofi-Aventis / leflunomide  HCA 50, so that gives us no guidance one way or the other.
In the end, the FCA’s view that Tennessee Eastman is authority for the proposition that methods of medical treatment are not patentable is certainly a reasonable interpretation of that decision, but at the same time I am confident that the SCC would not feel itself bound by Tennessee Eastman to hold that methods of medical treatment are not patentable, if that question came before it today.
With all that said, given that the FCA has consistently maintained its view of Tennessee Eastman since ICI (1986) 9 CPR(3d) 289, it is clearly settled at the FCA level that methods of medical treatment are not patentable, and unless and until the SCC grants leave, the more pressing question is "What is a method of medical treatment"?
In my view, to answer this question it is essential to have a clear understanding of the rationale for the exclusion of methods of medical treatment. As noted, text, context and purpose are all important to statutory interpretation, and when the text at issue, namely “art” or “process,” is ambiguous, purpose plays a correspondingly more important role. Unfortunately, we do not have any clear rationale for the exclusion.
The rationale that methods of medical treatment are “essentially non-economic” has support in the jurisprudence, but it a fiction which provides absolutely no guidance as to where to draw the line between claims which are patentable and those which are not.
The rationale with probably the most support in the jurisprudence worldwide, is that medical practitioners should not be restrained from treating patients according to their best medical judgment out of fear of a patent infringement action. This rationale does provide guidance as to what kinds of claims should be unpatentable. It implies that claims which cannot be infringed by doctors should be patentable. This rationale also has some support in Wellcome / AZT 2002 SCC 77. Regardless of what it said about methods of medical treatment generally, the SCC was very clear that the claim at issue which was “A pharmaceutical formulation for use in the treatment or prophylaxis of AIDS comprising an effective amount of [AZT],” was not a method of medical treatment:
50 The AZT patent does not seek to "fence in" an area of medical treatment. It seeks the exclusive right to provide AZT as a commercial offering. How and when, if at all, AZT is employed is left to the professional skill and judgment of the medical profession.
However, on this rationale the Swiss form claims at issue in Cobalt / zolendronate should have been patentable, as explained in my post on Hughes J’s decision.
A third rationale, adopted by Hughes J in the Cobalt / zolendronate is that claims which "include that which lies within the skill of the medical practitioner” are unpatentable  However, as I also discussed in my post on Hughes J’s decision, Hughes J interpreted this as meaning that any claim which requires medical skill to implement the invention is therefore unpatentable. So, the ‘201 patent at issue in this case directed that precise dosage “may be selected by the attending physician” , and therefore medical skill was required to practice the invention. Hughes J concluded that this meant the claims lay within the skill of the medical practitioner and were therefore unpatentable. However, this is very difficult to reconcile with the claim at issue in Wellcome / AZT which in the claim itself specified an “effective” amount of AZT. Determining the amount that is “effective” clearly requires the exercise of medical skill.
In summary, while we know that methods of medical treatment are not patentable, there is no clear rationale for this rule, and without a rationale, the scope of its application remains arbitrary and uncertain.