The Canadian Intellectual Property Office (CIPO) recently released a new Practice Notice that changes how patent examiners should assess whether an invention is eligible for a patent. This update is especially important for anyone working with computer-implemented inventions, medical diagnostic methods, or medical uses. Notably, the new guidance also provides examples of claims that are and are not considered patentable.
Why the Guidance Changed
The Practice Notice, released on March 24, 2026, responds to three recent court decisions about patentable subject matter. In the most recent case – Dusome v. Canada (Attorney General), 2025 FC 1809 – the Federal Court ruled that the Commissioner of Patents had made an error by focusing on what they believed was the inventor’s “actual invention,” rather than properly interpreting the claims using “purposive construction.”
To address this, CIPO has replaced its 2020 Practice Notice and shifted part of the “what was actually invented” analysis into an earlier stage of claim interpretation.
Purposive Construction
In purposive construction, an attempt is made to determine the nature of the invention, which may require reference to the entire disclosure. Consideration is given as to whether elements of a claim are described as being well-known or presented with little or no detail, suggesting that they belong to common general knowledge. Consideration is also given to what the inventor has “actually invented,” but this occurs before the analysis shifts to determining whether the subject matter meets the legal requirements for patentability.
Patentable Subject Matter Assessment
Once a claim is interpreted, the analysis turns to whether the subject matter is patentable. For a claim to qualify, it must fall within a statutory invention category, must not be limited to a mere scientific principle or abstract theorem, and must not fall into an excluded category such as a method of medical treatment.
Even if a claim contains an abstract idea or scientific principle, it may still be patentable if it forms part of a practical application that has physical existence or manifests a discernible effect or change. CIPO maintains that a “discernible effect” must be physical in nature.
Computer-implemented Inventions
The Practice Notice provides detailed guidance for computer-implemented inventions. Examiners first are to consider whether the invention has any physicality outside the computer, such as a sensor that measures something in the real world or equipment that produces a physical output. If so, the physicality requirement should be met.
If, on the other hand, the invention does not extend beyond the computer, the analysis turns to what CIPO now calls the “Schlumberger question,” and which now features more prominently in the analysis. Specifically, examiners must consider whether the invention simply processes an abstract algorithm in a well-known manner, or whether it improves the computer’s own functioning. Improvements in the computer’s function might relate to the computer's general performance, such as reducing memory usage, or to its performance in a specific task, such as speeding up a mathematical simulation. Under the new guidance, if the invention lacks any physicality beyond the computer, “something more” is required: the invention must use the computer in a way that meaningfully improves its functioning. When such an improvement exists, the use of the computer forms part of what the inventor has discovered and provides the necessary physicality for patentability.
The Schlumberger Question
The Schlumberger question stems from the 1981 Federal Court of Appeal decision in Schlumberger Canada Ltd. v. Commissioner of Patents, 1981 CanLII 4718 (FCA), which rejected a claimed invention because it amounted to a mere mathematical calculation carried out on a computer. Interestingly, and despite its prominent role in shaping patentable subject matter analysis in Canada, the actual claims at issue remain difficult to find today because applications at the time remained secret until grant. Claim 1 of that application recited “A machine operated method of processing well logging data” comprising an input step of “deriving a plurality of measurements representative of characteristics of an earth formation at selected depth levels over a section of a borehole”, various data processing steps, and an output step of “machine combining at least some of said derived measurements with said at least one output parameter ... to produce output parameters representative of at least one formation characteristic.” The deriving step may be understood to mean obtaining data without specifying that a sensor was used in obtaining the data. Likewise, the output step may be understood to produce data but does not specify that any equipment is used, or physical step is caused, outside the computer. In the second stage of the analysis, if the invention lacks any physicality beyond the computer, examiners must ensure it is not simply an abstract algorithm implemented on a computer in a routine way.
Application to Other Technologies
The Practice Notice applies a similar approach to inventions involving medical diagnostic methods and medical uses. The concept of physicality remains important, but the Notice also reaffirms the longstanding rule that methods of medical treatment are excluded from patentability in Canada.
Examples to Consider
The examples included with the Notice illustrate a handful of acceptable claim structures across different technologies. One example involving artificial intelligence explains that generating an irrigation schedule is considered to simply provide advice and does not meet the physicality requirement. However, consistent with the guidance, adding irrigation equipment for irrigating the crop according to the irrigation schedule does provide the necessary physicality.
Key Takeaways
Although the Notice does not attempt to address every kind of technological improvement, it suggests that many innovations will qualify when applicants provide clear, tailored explanations. It also incorporates several recommendations from the Intellectual Property Institute of Canada, particularly in its treatment of inputs and outputs, and it effectively preserves numerous favourable decisions of the Patent Appeal Board.
The full text of the Practice Notice and its accompanying examples are available on CIPO’s website.
If you would like to discuss strategies for protecting computer-implemented inventions or other patentable subject matter in Canada, our patent team would be pleased to assist.
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