Pharmascience v Janssen: Supreme Court of Canada Clarifies Patentability of Methods of Medical Treatment

On July 17, 2026, the Supreme Court of Canada (the Court) released its decision in Pharmascience Inc v Janssen Inc.[1] The decision – the Court's most direct consideration of methods of medical treatment in decades – provides important guidance concerning the boundary between patentable and unpatentable subject matter in the medical context. It also addresses longstanding uncertainty regarding the patentability of medical use claims defined by dosage regimens.

In this article, we summarize the Supreme Court of Canada’s decision and discuss its practical implications for medical use claims and methods of medical treatment.

Key Takeaways

• Methods of medical treatment remain unpatentable subject matter under Canadian law.
• In determining whether a claim encompasses an unpatentable method of medical treatment, the “ultimate question” is whether the claim seeks to monopolize professional medical skill and judgment. The Court identified three considerations that may assist with this determination.
• Claims incorporating dosage strengths and/or administration schedules defined by a range or window are not categorically unpatentable. Such features must be considered in the context of the ultimate question of whether the claimed subject matter amounts to professional medical skill and judgment.

Background

The underlying proceedings concern Janssen's Canadian Patent No. 2,655,335 (335 Patent), which relates to dosing regimens for a long-acting injectable formulation of paliperidone palmitate used in the treatment of schizophrenia and related disorders. The patent includes both medical use and product claims that incorporate those dosing regimens. 

Janssen markets a product covered by the patent in Canada under the brand name INVEGA SUSTENNA.

Janssen commenced patent infringement proceedings after Pharmascience sought regulatory approval to market a generic version of INVEGA SUSTENNA. In response, Pharmascience challenged the patent's validity on several grounds, including that the asserted claims were directed to unpatentable methods of medical treatment.

At trial,[2] the Federal Court held that Pharmascience's product infringed the 335 Patent and rejected Pharmascience's invalidity allegations. With respect to patentable subject matter, the trial judge concluded that the asserted claims did not require the exercise of professional skill and judgment and therefore did not constitute unpatentable methods of medical treatment. The Federal Court of Appeal dismissed[3] Pharmascience's appeal and affirmed the trial judge's conclusions, while observing that the determination of whether a dosing regimen constitutes a method of medical treatment cannot be based solely on whether the dosage amounts and administration schedule are fixed or variable.

Pharmascience appealed to the Supreme Court of Canada solely on the issue of whether the asserted claims encompassed unpatentable methods of medical treatment.

The Supreme Court’s Decision

Methods of Medical Treatment Remain Unpatentable

Before the Supreme Court, the parties (and several intervenors) took the opportunity to address the broader principles underlying the exclusion of methods of medical treatment from patentability. Pharmascience urged the Court to broaden the test for unpatentable methods of medical treatment. In contrast, Janssen challenged the continued rationale for the exclusion and argued that methods of medical treatment should not be treated as a distinct category of unpatentable subject matter.

The Supreme Court unanimously dismissed the appeal and upheld the validity of the 335 Patent. While the Court agreed on the outcome, it divided on the question of whether methods of medical treatment should continue to be excluded from patentable subject matter. 

In particular, a seven-judge majority reaffirmed that methods of medical treatment remain unpatentable. In doing so, the majority rejected the argument that the doctrine disappeared with the repeal of former section 41 of the Patent Act. According to the majority, the exclusion is rooted more broadly in the principle that professional medical skill and judgment do not constitute patentable subject matter.[4] 

In concurring reasons, the remaining two judges held that methods of medical treatment are not inherently excluded from patentability and should be assessed in the same manner as any other claimed invention.[5]

The “Ultimate Question” – Professional Medical Skill and Judgment

Having reaffirmed the continued existence of the exclusion, the majority turned to the question of how unpatentable methods of medical treatment are to be identified.

The Court rejected both Pharmascience’s proposed approach, which focused on whether claims dictate how and when a medical treatment is administered, and Janssen’s position that claims directed to dosing regimens are necessarily patentable. Instead, the Court adopted what it described as a balanced approach that seeks to distinguish between professional medical skill and judgment, which is not patentable, and other medical innovations.[6]

According to the Court, the “ultimate question” in determining if a claim encompasses unpatentable methods of medical treatment is whether the claimed subject matter amounts to professional medical skill and judgment. The Court emphasized that the analysis must be directed to the “real subject matter of the claim” as determined through purposive construction, rather than the form in which the claim is drafted.[7] 

While declining to establish a definitive test, the Court identified the following three considerations that may assist with this determination:[8]

1. The need for professional skill and judgment in determining whether the subject matter is or continues to be an appropriate treatment option for a particular patient will generally not affect its patentability.
2. The more the subject matter involves tailoring treatment to individual patients, the more likely it is that it amounts to a method of medical treatment.
3. The more a medical professional would be able to develop or improve the subject matter in the ordinary course of treating patients, the more likely it is that the subject matter constitutes a method of medical treatment.

The Court stressed that these considerations are not exhaustive and do not establish bright-line rules. Whether a claim encompasses an unpatentable method of medical treatment will depend on the nature of the claims and the facts of the particular case.[9]

Application to Dosage Regimens

The Court went on to consider how the foregoing principles apply to claims that recite dosage regimens. 

While the majority held that dosage regimens are not automatically patentable, it rejected the notion that patentability turns on a categorical distinction between fixed and variable dosage regimens. According to the Court, whether a claim covers fixed versus variable dosing is, at best, an evidentiary proxy that is sometimes useful but never dispositive of whether the claims are for unpatentable methods of medical treatment. Such features must be considered in the context of the ultimate question of whether the claimed subject matter amounts to professional medical skill and judgment.[10]

Applying the foregoing framework, the Court concluded that the asserted claims of the 335 Patent did not encompass unpatentable methods of medical treatment and were therefore valid. The majority accepted that the claimed dosage amounts and administration schedules did not require the exercise of professional medical judgment in implementing the claimed dosing regimens.[11]

Practical Implications

The decision confirms that the analysis of methods of medical treatment claims must focus on whether the claimed subject matter amounts to professional medical skill and judgment. In doing so, the Court rejected rigid distinctions between fixed and variable dosage regimens and confirmed that claims incorporating dosage strengths and/or administration schedules defined by a range or window are not categorically unpatentable. Although the Court reaffirmed that methods of medical treatment remain outside the scope of patentable subject matter, it largely endorsed the analytical direction that had emerged from the Federal Court and Federal Court of Appeal in recent years. The decision therefore provides important guidance for future cases involving dosage regimen claims and other medical use claims.

If you have any questions regarding this decision or its implications for patent prosecution, patent litigation, or life sciences intellectual property strategy, please contact a member of the Marks & Clerk patents and life sciences groups in Canada.

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