Choueifaty: A “solution” to a “problem” for computer-implemented and medical diagnostic method inventions

Federal Court rejects problem/solution approach to claims construction

The Federal Court of Canada has rendered a pivotal decision on claims construction in Choueifaty v. Canada (Attorney General) (Choueifaty)1, which will be welcome news to innovators in the software and medical diagnostic fields. In rejecting the “problem/solution” approach to claims construction, the Choueifaty decision is expected to have significant consequences for the Canadian Intellectual Property Office (CIPO) practice standards pertaining to examination of computer-implemented and medical diagnostic inventions.

What you need to know

  • The Federal Court has rejected the CIPO’s “problem/solution” approach to claims construction and determining patent-eligible subject-matter, finding that the correct legal standard has already been established by the Supreme Court of Canada in the Whirlpool and Free World Trust decisions.
  • The Choueifaty decision is expected to significantly alter the CIPO’s examination practices, particularly with respect to patent applications for computer-implemented and medical diagnostic methods.
  • Applicants should continue to take care in drafting computer-implemented or medical diagnostic method applications, keeping in mind the established law for essential element and statutory subject-matter determination.

The Choueifaty decision

This is an appeal of a decision of the Commissioner of Patents, refusing Canadian patent application no. 2,635,393 (the ‘393 Application) on the basis that its essential claim elements are directed to non-statutory subject matter.  The Court held that in employing the problem/solution approach, the Commissioner did not apply the proper test in purposively construing the claims of the ‘393 Application to determine its essential elements. The Court set aside the decision of the Commissioner with instructions to do a fresh assessment of the ‘393 Application2.


The test for determining whether essential claim elements comprise statutory subject-matter was established by the Federal Court of Appeal in Canada (Attorney General) v. Inc., 2011 FCA 328 (Amazon)3. The Court held that “it is implicit in the definition of “invention” that patentable subject matter must be something with physical existence, or something that manifests a discernible effect or change” (emphasis added), and further, that a new method can be “one of a number of essential elements in a novel combination”4.

Following the Amazon decision, in 2013, the CIPO issued a guidance document (Practice Notice PN2013-02)5 reflecting its interpretation of Amazon and the jurisprudence regarding the construction of claims in a patent application. In accordance with the established case law, PN2013-02 mandates a purposive approach to claims construction in order to identify essential claim elements. However, more controversially, PN2013-02 further requires examiners to identify essential elements by identifying from the patent description the problem the inventors set out to solve, and its proposed solution, with the essential claim elements being those elements required to effect the identified solution. This “problem/solution” approach required by PN2013-02 does not appear to have basis in case law, and underpins subsequently issued examination guidance documents applying the problem/solution approach to computer-implemented and medical diagnostic inventions (Practice Notices PN2013-03 and PN2015-026 respectively), which often form the basis for subject-matter objections for inventions in these fields.

In reviewing the ‘393 Application, the CIPO relied on PN2013-03 in applying the problem/solution approach to determine the essential claim elements to comprise a scheme or rules involving mere calculations. The CIPO considered the claims to therefore lack a discernable physical effect and thus to be directed to non-patentable subject-matter7. The applicant appealed this CIPO determination to the Federal Court.

In its analysis, the Choueifaty Court appears to be rebuking the Commissioner, stating that “[i]t is evident on a reading of the MOPOP [Manual of Patent Office Practice] that the Commissioner, notwithstanding stating that the patent claims are to be construed in a purposive manner, does not intend or direct patent examiners to follow the [Supreme Court of Canada] teachings of Free World Trust and Whirlpool8.

The Court remarked that the problem/solution approach is akin to the discredited “substance of the invention” approach to claims construction, and rejected it as the proper approach to claims construction in Canada. The Court went on to confirm the correct principles for claims construction and determining essential elements that were established in Free World Trust:

  1. Would it be obvious to a skilled reader that varying a particular element would not effect [sic] the way the invention works? If modifying or substituting the element changes the way the invention works, then that element is essential.
  2. Is it the intention of the inventor, considering the express language of the claim, or inferred from it, that the element was intended to be essential? If so, then it is an essential element9.

In holding that the Commissioner erred in applying the problem/solution approach to determine essential claim elements, the Court noted that the problem/solution approach focuses only on the first aspect of the above test, while ignoring the second10. The Court thus found the problem/solution approach to be inconsistent with the correct principles for claims construction.


Absent an appeal reversing it, the Choueifaty decision is expected to result in significant changes to examination practice standards at the CIPO, particularly for fields in which the CIPO practice notices on purposive claims construction are traditionally applied: computer-implemented and medical diagnostic methods. Although the decision did not explicitly address the issue of patentable subject-matter, the comments on claims construction may prove helpful in overcoming subject-matter objections in these fields.

It remains to be seen how the CIPO will interpret the Choueifaty decision, and how soon it will update its examination guidance (including whether it will update or withdraw PN2013-02, PN2013-03 and PN2015-02). In the meantime, applicants should continue to take care in crafting computer-implemented or medical diagnostic method applications, keeping in mind the established law for essential element and statutory subject-matter determination.



2 Choueifaty at paras. 2 and 43.


4 Amazon at paras. 63 and 66.


6 and

7 Choueifaty at paras. 14 to 18.

8 Ibid. at para. 31, citing the Canadian Manual of Patent Office Practice [MOPOP], Free World Trust v. Électro Santé Inc., [2000] 2 SCR 1024, 2000 SCC 66 [Free World Trust] and Whirlpool Corp. v. Camco Inc., [2000] 2 S.C.R. 1067; 2000 SCC 67 [Whirlpool].

9 Ibid. at para. 38.

10 Ibid. at paras. 39 and 40.

To discuss these issues, please contact the author(s).

This publication is a general discussion of certain legal and related developments and should not be relied upon as legal advice. If you require legal advice, we would be pleased to discuss the issues in this publication with you, in the context of your particular circumstances.

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