On October 9, 2025, the Supreme Court of Canada heard oral arguments in Pharmascience Inc. v. Janssen Inc. (SCC File No. 41209), a case that could fundamentally reshape what qualifies as a patentable invention in Canada. At stake is a question that has vexed Canadian courts for over fifty years: can methods of medical treatment, specifically dosage regimens, be patented?
The Court’s decision will have far-reaching implications not only for pharmaceutical and biotechnology companies but for innovators across all sectors. Understanding complex patent eligibility questions requires guidance from an experienced Toronto-based intellectual property law firm with deep expertise in Canadian patent litigation. At its core, this case asks the Supreme Court to revisit foundational principles of patent eligibility, principles that affect how businesses protect and commercialise their innovations in Canada.
This article examines the legal questions before the Court, the competing arguments from the parties and interveners, and what the outcome could mean for patent strategy in Canada. Whether you are an in-house counsel, a C-suite executive, or a patent portfolio manager, understanding this case is essential preparation for potential shifts in Canadian patent law.
The Patent at Issue: INVEGA SUSTENNA and the ‘335 Patent
The dispute centres on Canadian Patent No. 2,655,335 (the “‘335 Patent”), which was issued to Janssen Pharmaceutica N.V. for INVEGA SUSTENNA, a long-acting injectable suspension of paliperidone palmitate used to treat schizophrenia and related disorders.
The ‘335 Patent does not claim the drug itself, paliperidone palmitate was already known. Instead, the patent claims a specific dosing regimen designed to achieve an optimal plasma concentration-time profile. The claimed regimen includes a first loading dose, a second loading dose (within a dosing window of ± 2 days), and monthly maintenance doses (within a dosing window of ± 7 days).
Pharmascience, a generic pharmaceutical manufacturer, sought regulatory approval to market pms-PALIPERIDONE PALMITATE, its proposed generic version of INVEGA SUSTENNA. Janssen commenced an infringement action under section 6(1) of the Patented Medicines (Notice of Compliance) Regulations. Pharmascience defended on the basis that the ‘335 Patent was invalid for claiming an unpatentable method of medical treatment.
The Lower Court Decisions
Federal Court Decision (2022 FC 1218)
The Federal Court upheld the validity of the ‘335 Patent. Justice Walker found that the patent claims were not invalid for obviousness or for lack of patentable subject matter. The Court concluded that the claims provided specified dosing regimens intended to produce a concentration of the medication within the therapeutic range. Critically, the Court found that if a physician chose to use a dose other than that claimed, stop treatment, or change therapies, they would no longer be practising the claimed invention.
Federal Court of Appeal Decision (2024 FCA 23)
The Federal Court of Appeal dismissed Pharmascience’s appeal. Writing for the Court, Justice Locke found that the use of the invention did not require the exercise of skill and judgment by a physician, a key factor that had been used in prior cases to distinguish patentable dosing claims from unpatentable methods of medical treatment.
Pharmascience subsequently sought leave to appeal to the Supreme Court of Canada. Leave was granted on September 19, 2024, with costs in the cause, signalling the Court’s recognition of the national importance of the legal questions at issue.
The Historical Context: Tennessee Eastman and Section 41
To understand the significance of Pharmascience v. Janssen, one must first understand the 1974 Supreme Court decision in Tennessee Eastman Co. v. Commissioner of Patents, [1974] S.C.R. 111, the leading authority for the proposition that methods of medical treatment are not patentable in Canada.
In Tennessee Eastman, the Supreme Court rejected a patent application for a surgical method of bonding wound tissue using certain adhesive compounds. The compounds themselves were not new; the novelty lay in their application to surgical wound closure. The Court held that methods of medical treatment are not contemplated in the definition of “invention” as a kind of “process” under the Patent Act.
Critically, the Tennessee Eastman decision relied heavily on section 41 of the Patent Act (R.S.C. 1970, c. P-4), which restricted the scope of patents “relating to substances prepared or produced by chemical processes and intended for food or medicine.” The Court reasoned that, with respect to such substances, a medical or therapeutic use could not be claimed by a process claim apart from the substance itself.
However, section 41 has since been repealed. This raises a fundamental question: if patent law in Canada is “wholly statutory” (as the Supreme Court has repeatedly affirmed), does the principle established in Tennessee Eastman survive the repeal of the very statutory provision upon which it was based?
The Legal Questions Before the Supreme Court
The appeal presents two central questions:
1. Are methods of medical treatment patentable in Canada? This question asks whether the prohibition established in Tennessee Eastman remains valid law, or whether it should be reconsidered in light of the repeal of section 41.
2. What is a method of medical treatment, or what test should guide its determination? If some preclusion exists, how should courts distinguish between unpatentable methods of medical treatment and patentable dosing regimens or pharmaceutical products?
The Competing Arguments
Pharmascience’s Position
Pharmascience submits that methods of medical treatment are not patentable, as established by Tennessee Eastman. It contends that this principle remains settled law and is rooted in the Patent Act‘s requirement that a patent may only be granted for an “invention,” which does not encompass methods of medical treatment.
Pharmascience proposes a test for determining whether a patent claims a method of medical treatment: (a) construe the claim in accordance with normal procedures; (b) identify whether any essential elements of the claim can properly be said to be “therapeutic” or “medical”; and (c) identify whether any of those essential elements relate to how and when a drug or treatment is to be administered by a medical practitioner. If the answers to (b) and (c) are “yes,” then the claims are invalid for claiming unpatentable subject matter.
Janssen’s Position
Janssen argues that the historical basis for excluding claims to methods of medical treatment, the Tennessee Eastman decision, is based upon a provision of the Patent Act that has since been repealed. Since patent law is wholly statutory, Janssen submits there is no longer any valid legal basis to preclude claims for a method of medical treatment.
Janssen also submits that methods of medical treatment fall within the broad interpretation of “invention” as defined in the Patent Act. It asks the Supreme Court to declare that there is no legal bar in Canada to claiming methods of medical treatment.
In the alternative, Janssen argues that if a preclusion exists, it should be limited in scope to apply only to non-economic medical activities unrelated to commercial products. Janssen submits that the ‘335 Patent is not directed to such non-economic activities and is therefore valid.
The Interveners: A Range of Perspectives
The Supreme Court granted leave to intervene to five organisations, reflecting the broad interest in this case across the pharmaceutical industry, the medical profession, and patient advocacy groups.
Canadian Generic Pharmaceutical Association (CGPA)
The CGPA, an industry association representing generic pharmaceutical manufacturers, argues that dosing regimens are merely methods of treating patients and do not constitute an “invention” within the meaning of the Patent Act. The CGPA contends that granting patents for dosage regimens unduly extends the monopoly over a drug and prejudices Canadians by contributing to higher medicine prices.
Canadian Organization for Rare Disorders (CORD)
CORD, a network of patient organisations representing those with rare disorders, submits that the Patent Act permits claims directed to methods of medical treatment. CORD argues that since Parliament has repealed the statutory provision central to the Tennessee Eastman decision, the prohibition no longer applies. CORD emphasises that recognising the patentability of methods of medical treatment is essential to incentivising pharmaceutical companies to develop new treatments.
Innovative Medicines Canada and BIOTECanada
These industry associations representing innovative pharmaceutical and biotechnology companies support Janssen’s position that methods of medical treatment should be patentable in Canada, consistent with the approach in many other jurisdictions.
International Federation of Intellectual Property Attorneys (FICPI)
FICPI provides an international perspective on patent eligibility standards, highlighting how Canada’s approach compares to those of other major patent jurisdictions.
Drs. Homuth, Solmi, and Bleau (Physician Interveners)
These Canadian physicians involved in treating patients with dosing regimens such as those described in the ‘335 Patent submit that new medicines and dosing regimens are not developed by physicians but are the result of commercial innovation by pharmaceutical manufacturers. They argue that recognising the patentability of dosing regimens is essential to incentivising pharmaceutical companies to develop new treatments for the benefit of Canadian patients.
Implications Beyond Pharmaceuticals
While Pharmascience v. Janssen is a pharmaceutical patent case, the Supreme Court’s reasoning on patentable subject matter could have implications far beyond the life sciences sector.
The definition of “invention” under section 2 of the Patent Act includes “any new and useful art, process, machine, manufacture or composition of matter, or any new and useful improvement in any art, process, machine, manufacture or composition of matter.” How the Court interprets the scope of “process” and “art” in this case could affect patent eligibility determinations for:
• Artificial intelligence and software inventions – Recent decisions from the Patent Appeal Board (including 2025 CACP 8, which confirmed that AI cannot be an inventor in Canada, and 2025 CACP 9 and 2025 CACP 10, which rejected computer-implemented colour selection patents) have addressed the boundaries of patentable subject matter for digital technologies.
• Business methods and professional services – The distinction between patentable inventions and unpatentable “professional skills” or “fine arts” may be clarified.
• Biotechnology and personalised medicine – As treatments become more tailored to individual patients, the line between a “vendible product” and a “method of treatment” may become increasingly blurred.
What This Means for Your Business
Regardless of how the Supreme Court rules, businesses with Canadian patent portfolios or market entry plans should consider the following:
For Innovators and Patent Holders
If the Court affirms that methods of medical treatment can be patented, dosage regimen patents may become a more reliable form of protection for pharmaceutical innovations. This could encourage investment in clinical research to develop optimised dosing protocols. If the Court narrows or eliminates the preclusion, patent drafting strategies should be reviewed to ensure claims are framed as broadly as the new legal landscape permits.
For Generic and Biosimilar Manufacturers
If the Court maintains a broad prohibition on methods of medical treatment, challenges to dosage regimen patents may become more viable. However, if the Court adopts a narrow “skill and judgment” test, product monograph drafting and market entry strategies will need to be carefully calibrated to avoid infringement findings.
For Technology Companies
The Court’s reasoning on the scope of “invention” and the interplay between statutory language and judicial interpretation could provide guidance for ongoing debates about the patentability of AI-related inventions, software, and computer-implemented methods.
What Happens Next
The Supreme Court reserved its decision following the October 9, 2025 hearing. There is no fixed timeline for when the Court will release its reasons, but decisions in significant patent cases typically issue within six to twelve months of the hearing.
Businesses should monitor this case closely. The outcome will affect not only pending litigation but also patent prosecution strategies, licensing negotiations, and product launch planning across the Canadian market.
Conclusion
Pharmascience v. Janssen represents a rare opportunity for the Supreme Court of Canada to revisit foundational principles of patent eligibility. After more than fifty years, the question of whether methods of medical treatment can be patented may finally receive definitive resolution.
For innovators, the stakes are high. A decision affirming the patentability of dosage regimens could strengthen protection for pharmaceutical R&D investments. A decision maintaining a broad prohibition could limit the scope of available patent protection in Canada compared to other major jurisdictions.
Whatever the outcome, businesses operating in the Canadian market should prepare for potential shifts in how patents are obtained, enforced, and challenged. Early engagement with experienced patent litigation counsel is essential to navigating this evolving landscape.
