On 25 March 2026, the Canadian Intellectual Property Office (CIPO) issued further guidance on the Patent Office’s understanding of patentable subject matter in relation to computer-implemented inventions, medical diagnostic methods, and medical uses. The practice notice comes in light of a number of notable recent court decisions, including Canada (Attorney General) v Benjamin Moore & Co, 2023 FCA 168; Dusome v Canada (Attorney General), 2025 FC 1809; and Pharmascience Inc v Janssen Inc, 2024 FCA 23.
This guidance supersedes existing guidance within the Manual of Patent Office Practice (MOPOP) relating to the “contribution” of a claim, to a “technological solution to a technological problem”, and to evaluating essentiality of elements based on a “problem and solution” during purposive construction. This is likely in response to explicit articulations by Canadian Courts against CIPO’s previous applications of a “problem-solution” and “actual invention” approach for determining patentable subject matter.
The present guidance also supersedes earlier practice notice PN2020-04 on patentable subject matter, issued on November 3, 2020.
Purposive construction and the “actual invention”
The March 2026 practice notice begins by outlining the basic principles of purposive construction but underscores certain considerations in determining the nature of the invention. Namely, the Patent Office emphasizes that: 1) claim features that are characterized in the specification as being well-known or used in a conventional way, or that are described with minimal detail, may constitute common general knowledge (CGK); and 2) in a number of situations, asking what the inventor has actually invented, or what the inventor claims to have invented, is relevant and necessary; the latter of which appears to simply rephrase the “actual invention” approach refuted by the courts.
Based on the published examples, it appears the Patent Office will apply these principles by treating certain claim elements as part of the CGK based on their characterization, or lack thereof, in the specification. For instance, where the description provides little to no detail on programming aspects, how a claimed algorithm or neural network structure is programmed may be taken by the Patent Office as being CGK.
Standard for patentable subject matter: the primacy of physicality
The guidance goes on to reaffirm what the Patent Office considers to be patentable subject-matter: that which includes a disembodied idea, a scientific principle or an abstract theorem that is part of a practical application that has physical existence or manifests a discernible effect or change, and is not judicially excluded. The term “discernible” is clarified as referring to “physical” effects or changes, which CIPO views as being “implicit in the definition of ‘invention’”. These guidelines seem to further reinforce CIPO’s focus on a clear physicality requirement for patentability, which appears to deviate from standards imposed in other jurisdictions such as the United States, as well as guidance that CIPO has received from the Canadian courts.
Computer-implemented inventions vs the “Schlumberger question”
With respect to computer-implemented inventions, the practice notice confirms that where there are additional physical essential elements such as a measurement step or sensor, or output means, the physicality requirement is generally met.
Interestingly, the March 2026 guidance proposes asking “the Schlumberger question” in cases where CIPO considers there to be no physicality outside of the computer system elements. In essence, the Schlumberger question compares the invention under consideration against Schlumberger Canada Ltd v Commissioner of Patents, 1981 CanLII 4718 (FCA), [1982] 1 FC 845 (where a mathematical calculation was considered to simply be programmed into a computer) and asks if the situations can be distinguished.
In applying the Schlumberger question, the Patent Office seeks to identify “what, according to the application, has been discovered”. If what has been discovered is “only an abstract algorithm or abstract set of rules”, then the algorithm being programmed into the computer is considered to provide a “bare practical application” and is not distinguished from Schlumberger. Instead, “something more” is required to meet the physicality requirement.
Notably, if processing the algorithm results in any improvement to the functioning of the computer, then CIPO considers what has been discovered as more than a bare practical application. The improvement may be to the computer's operation for tasks in general, such as an improved operating system that reduces memory usage, or an improvement to the task at hand, such as mathematical manipulations that speed up a mathematical simulation. Under the guidance of the Patent Office, the improved computer and its improved functionality impart physicality to the invention.
Computer implemented patentable subject matter examples
Computer-implemented example 1 – a method of analyzing data from seismic measurements.
Claims of example 1 that are directed to performing seismic measurements, use of seismic sensors, or a step of drilling for oil are found to be eligible.
Claim 3 is directed to a processor configured to analyze seismic measurement data using algorithm X and cause a display to provide resulting recommended drilling site locations. Under CIPO’s new Schlumberger question, even though the claimed algorithm improves the drilling site identification, the Patent Office does not consider it to cause any discernible effect, change in the external world or internally to the processor.
Computer-implemented example 2 – A method of choosing an investment portfolio with a mix of asset classes to meet return and risk criteria
Claim 1 of example 2 is directed to a method that uses a computer to generate asset-class return scenarios, map financial products to asset classes, simulate portfolio returns and optimize portfolio selection. Under CIPO’s purposive construction, this claim involves merely “applying algorithm A to simulated returns based on economic factors to better determine an investment portfolio meeting certain requirements”, and is not distinguished from Schlumberger.
In contrast, claim 2 is directed to applying transform B in the application of algorithm A. According to CIPO, use of transform B in conjunction with algorithm A improves the functioning of the computer in a discernible manner (by reducing the number of arithmetic operations in computing algorithm A), and is therefore seen as providing more than a bare practical application of an otherwise abstract algorithm and transform.
Computer-implemented example 3 – a system for determining an irrigation schedule for a crop planted at a location.
Claim 1 of example 3 includes data input means, a database X, data output means, and a processor. The processor implements the steps of inputting to the processor historical data from database X, training neural network prediction algorithm V to optimize irrigation parameters, inputting recent data Y to the trained neural network prediction algorithm V and outputting a recommended irrigation schedule.
Under CIPO’s purposive construction, no aspect of the neural network prediction algorithm V addresses any issue related to machine learning or computing-based on the specification. Considering this construction, the claim does not stand up against the Schlumberger question, as the input is considered to be data and the output to be irrigation “advice” that has no physicality in and of itself. As such, this claim is not directed to patentable subject matter.
Claim 2 is directed to irrigation means according to the recommended irrigation schedule, which is considered to involve an additional physical element and therefore meets the external physicality requirement.
Medical diagnostic methods
CIPO’s guidance on the patentability of medical diagnostic methods is largely unchanged from the earlier PN2020-04. Diagnostic methods often include a correlation, such as the level of a biomarker with a particular disease outcome. Correlations, on their own, are an abstract or disembodied idea, which is not considered patent-eligible subject matter. However, where the otherwise abstract or disembodied diagnostic method satisfies the physicality requirement, the claim may be directed to patentable subject matter.
The March 2026 notice sets out exemplary elements such as measuring, identifying, detecting or assaying the presence or quantity of an analyte in a sample as providing the required physicality. Moreover, it is noted that where a computer is involved in the method, the considerations on computer-implemented inventions apply. While the computer may provide a practical application to the diagnostic method, it does not necessarily satisfy the physicality requirement without “something more” (see above).
Example
The example provided demonstrates two types of claims directed to determining the risk of developing cancer. In claim 1 the method includes measuring the expression levels of markers A, B and C in a biological sample from the subject and calculating a risk score based on the levels of A, B and C using equation X, wherein a risk score above Y indicates the subject is at risk for cancer. In claim 2, the method includes receiving, at a processor, expression levels of markers A, B and C in a biological sample from the subject and at the processor calculating a risk score based on the levels of A, B and C using equation X, wherein a risk score above Y indicates the subject is at risk for cancer. 1
The claims differ in that claim 1 includes physically measuring the expression levels in a sample, while claim 2 merely obtains data previously obtained from the sample. Accordingly, when the claims are construed, claim 1 is deemed to possess the required physicality and thus directed to patentable subject matter. In contrast, claim 2 merely uses a computer to receive data and make calculations in a well-known manner and does not satisfy the Schlumberger question.
Medical uses
The patentability of medical use claims continues to be an ongoing debate in Canada. As stated in the March 2026 notice, we await guidance from the Supreme Court of Canada (SCC) on the appeal of Pharmascience Inc v Janssen Inc 2024 FCA 23, which is expected to be released this year.
The March 2026 notice is in line with previous guidance that where a claim is construed to require the exercise of skill and judgment, or where an active medical treatment step or surgical step is an essential element, the claim is directed to non-patentable subject matter. Similar to the previous guidance in PN2020-04, it is noted that the patentability of dosage regimens cannot be determined solely based on whether the dosing and schedule is fixed or variable, however, it is noted that fixed dosage and schedule are often a good indicator that skill and judgement are not required.
Examples
The notice provides two examples of medical use claims.
The first example is directed to use of compound X to prevent asthma attacks, with a dependent claim indicating a dosage regimen for use at a daily dose of between 120 and 360 mg.
Both claims are directed to patentable subject matter, as neither require the exercise of skill and judgment. Regarding claim 2, reference to the specification indicates that dosages within the claimed range were well tolerated and effective.
The second example is directed to a titration dosing regimen for treating epilepsy. The claim recites use of compound X from a first dosage of 25 mg/day to a final dosage of 100 mg/day to 200 mg/day for treating epilepsy in a patient, wherein said first dosage is for use for a period from 1 to 12 weeks. In this case, the claim is considered to involve titration and the medical professional is required to continuously monitor and adjust the dosages and dosage period. Further, skill and judgment are considered to be required when progressing from the initial dose to the final dose. Accordingly, the claim is considered to be directed to a non-patentable method of medical treatment.
Key takeaways and practical applications
Applicants should take care to ensure that material aspects of their invention are clearly, strategically, and adequately disclosed in the specification and that physical elements such as measurement steps, sensors, and physical output means are incorporated and substantiated. If there is any improvement(s) to the functioning of a computer that may be imparted by the invention (e.g., decreased memory usage, a reduction in mathematical computations, etc.), such improvement(s) should be highlighted during prosecution, and supported by the description. Pharmaceutical applicants should consider including support for physical steps in diagnostic methods, such as providing and assaying a sample, though actually obtaining a sample (such as a tumor sample) from a patient cannot be claimed. It remains to be seen how echoes of earlier “problem-solution” and “actual invention” frameworks may continue to influence how the Patent Office assesses patentable subject matter under the updated guidance. While awaiting the release of SCC decision in Pharmascience v Janssen, medical uses continue to be assessed by whether they involve the exercise of skill and judgment. It remains to be seen how this decision will impact CIPO’s guidelines.
CIPO’s March 2026 practice notice may be found here, and the published examples may be found here.
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References
1. Emphasis Added