Status quo ante: Supreme Court of Canada affirms law on methods of medical treatment

The Supreme Court of Canada has released its highly anticipated decision in Pharmascience Inc. v. Janssen Inc.¹,  upholding the validity of Janssen’s patent for a long-acting dosing regimen for the treatment of schizophrenia. While both parties asked the court to do a major overhaul to the prohibition on patenting methods of medical treatment, a seven-judge majority left the law essentially intact: claims to methods of medical treatment are impermissible, but this prohibition is narrow, and only applies to claims that seek to monopolize “professional skill and judgement”.

What you need to know

• Methods of medical treatment remain unpatentable subject matter in Canada because they seek to monopolize professional skill and judgment, which is inconsistent with the purpose of the Patent Act.
• Whether a claim covers an unpatentable method of medical treatment turns on whether the claimed subject matter amounts to professional skill and judgment.
• There is no “bright line” or categorical rule about when such subject matter will be unpatentable: the analysis is inherently fact-specific.  
• In the context of dosing, a claim may be more defensible where flexibility in timing, dose, or administration does not require the application of clinical judgment—for example, to a class of patients without the need for individualized adjustment.

Background

Janssen owns Canadian Patent No. 2,655,335 (the 335 Patent), which relates to its drug INVEGA SUSTENNA, a long-acting injection of paliperidone palmitate used to treat schizophrenia and related disorders. The 335 Patent claims a dosing regimen designed to achieve an optimal blood plasma concentration of paliperidone over time. Pharmascience sought approval to market a generic version of Janssen's drug and claimed that the 335 Patent was unpatentable as a method of medical treatment (MMT).

Both the Federal Court² and the Federal Court of Appeal³ rejected this argument. The Court of Appeal concluded that whether a claim constitutes an unpatentable method of medical treatment turns on whether using the invention requires professional skill and judgment. Pharmascience appealed to the Supreme Court asking it to clarify the law on MMTs. The Supreme Court upheld the validity of Janssen’s 335 Patent because the claimed dosage regimen did not require professional skill and judgment to implement once selected.

Majority upheld both the patent and the current law on methods of medical treatment

Pharmascience proposed a test for MMTs that would invalidate patent claims directed to “how and when” a medical practitioner administers a drug or treatment. Janssen argued that the prohibition on MMTs should be abolished, since it was premised on former section 41(1) of the Patent Act, which has been repealed. The Supreme Court rejected both arguments, held that claims to MMTs remain invalid, and held that the test, fashioned by the Federal Court of Appeal, should not change.

MMTs remain unpatentable

The majority confirmed the prohibition on MMTs derives from the definition of “invention” in section 2 of the Patent Act⁴—a point confirmed by Tennessee Eastman Co.⁵, where the Supreme Court of Canada also discussed the now-repealed prohibition contained in subsection 41(1) (which precluded claims to medicines other than as process or product-by-process claims). The prohibition on patenting methods of medical treatment is, distinct from section 41, a specific application of the broader principle that professional skills unrelated to trade, industry, or commerce are not patentable subject matter.

Existing law affirmed

The Court confirmed the existing law (used by the Court of Appeal) for determining when a patent impermissibly claims a method of medical treatment. The Court confirmed that dosing regimens may, but do not necessarily, constitute patentable subject matter. It rejected any attempt to impose categorical restrictions: the distinction between fixed and variable dosages applied in prior cases was not dispositive. The "ultimate question" is whether the claimed subject matter amounts to professional skill and judgment: “[t]he inquiry is whether the claim seeks to ‘fence in’ an area of medical practice”⁶. The Court held that determining the patentability of a dosing regimen claim is a “factually suffused exercise that depends on the evidence as to how the dosing regimen is intended to be applied”⁷, and offered three non-exhaustive guidelines:

1. It is whether the subject matter of the claim amounts to professional skill and judgment—and not whether such judgment is exercised in selecting the clamed invention for a particular patient—that matters.
2. The more the claim involves tailoring treatment to individual patients, the more likely it is to be deemed a method of medical treatment.
3. The application of the test must remain focused on the purpose of the prohibition: “The more a medical professional would already be incentivized to develop or improve a given subject matter in the course of their professional practice, the more likely it is that the subject matter amounts to a method of medical treatment”.

The concurrence: MMTs should not be inherently unpatentable

Justices O'Bonsawin and Moreau agreed that the 335 Patent is valid, but with different reasoning. They would have abolished the prohibition on MMTs because of the repeal of former subsection 41(1). The minority would have imported the analysis as to whether such claims are valid into the traditional requirements for patentability: most notably, the utility requirement.

Analysis and implications

This decision does little to clarify the law. Arguably, it makes the law less clear: the lower courts had held that claims to a specific dosing regimen would be patentable, while claims to dosing ranges were unpatentable as MMTs. This was never satisfactory in theory, but it was a distinction that the industry could follow. The Supreme Court has re-affirmed the prohibition on MMTs, but eliminated the distinction that worked in practice, throwing some doubt on how to apply the test. So the argument remains, but with considerable ambiguity.

For innovators, the decision confirms that dosing regimen patents remain available in Canada, but careful claim drafting and evidentiary support will be critical. Claims will be stronger where (a) the dosing regimen can be applied generally to a class of patients without the need for adjustment at the individual patient level; and (b) any flexibility in timing, dose, or administration can be shown not to involve clinical judgment. For patent challengers, the decision preserves a viable invalidity argument where a claim, in substance, requires or monopolizes professional medical skill and judgment. However, the decision also makes clear that a challenger cannot rely categorically on the fact that a claim involves dosing, timing, or administration instructions.