On June 10, 2013, the Canadian Intellectual Property Office (“CIPO”) issued Practice Notice PN 2013-04 (the “Notice”), which provides guidelines to be followed in the examination of patent claims covering medical uses.

In Canada, methods of medical treatment are considered to fall outside the scope of the definition of “invention” provided by the Patent Act. Claims directed to such methods are, therefore, considered to be directed to non-patentable subject matter, and rejected as invalid during prosecution. However, certain forms of medical “use” claims, such as those directed to “use of [compound] for treatment”, “use of [compound] in the manufacture of a medicament for treatment” or “[compound] for use in treatment”, are generally considered to be valid, so long as no active treatment or surgical steps are recited. The Notice is intended to provide examiners specific guidance with respect to the examination of such “medical use” type claims.

As an introductory point, the Notice states that, although medical use claims will generally be allowed, when it is determined that such claims “prevent physicians from exercising their skill and judgment in using a known compound for an established purpose”, they will be considered to effectively cover a method of medical treatment, and should be rejected by the examiner. The Notice then goes on to provide guidance as to how examiners should evaluate claims in making such a determination.

Purposive Claim Construction

With reference to the 2011 Federal Court of Appeal decision in Canada (Attorney General) v. (“Amazon”), and to the recently issued Practice Notice PN 2013-02, the current Notice states that any patentable subject matter determination must be based on a purposive construction of the claim in issue. In this respect, the Notice may be considered a departure from past CIPO practice regarding patentable subject matter, which practice had relied on an assessment of the nature of the “contribution” of the claim.

The Canadian approach to purposive construction was established by the Supreme Court of Canada’s leading decision in Free World Trust v. Électro Santé Inc.In that decision, the Court stated that:

The claims language will, on a purposive construction, show that some elements of the claimed invention are essential while others are non-essential. The identification of elements as essential or non-essential is made:

  1. on the basis of the common knowledge of the worker skilled in the art to which the patent relates;
  2. as of the date the patent is published;
  3. having regard to whether or not it was obvious to the skilled reader at the time the patent was published that a variant of a particular element would not make a difference to the way in which the invention works; or
  4. according to the intent of the inventor, expressed or inferred from the claims, that a particular element is essential irrespective of its practical effect;
  5. without, however, resort to extrinsic evidence of the inventor’s intention.

By comparison, the purposive construction analysis set out in the Notice emphasizes the identification of the “problem the inventors set out to address and the solution disclosed”. In carrying out this analysis, the Notice instructs the examiner to consider what the inventors state about the background of the invention, their objectives, and specific problems, needs, limitations or advantages known in the art. The Notice states that the identification of the problem should be guided by the examiner’s understanding of the common general knowledge and the description itself.   

Patentability Determined Based on Nature of “Essential Elements”

After having identified the problem and solution, the Notice instructs the examiner to then determine which claim elements are “essential” and “non-essential” to the solution. If any of the so-identified “essential elements” is considered to instruct a medical professional “how” to treat a patient, that claim should be considered as being directed to a method of medical treatment, and therefore rejected by the examiner as invalid. By contrast, claim elements directed to “what” to use to treat the patient should not result in a finding of invalidity.

By way of example, the Notice lists several claim elements of particular interest to patent applicants interested in the rapidly developing field of personalized medicine, namely: dosing schedules; dosage ranges; limitations of treatment to a patient sub-population; and sites of administration, as “how” elements that, if deemed “essential” to a claim, should result in that claim’s rejection.  

Accordingly, the impact of the Notice on the patentability of medical use claims that recite limitations according to dosage, patient sub-population, and site of administration, is likely to depend on whether examiners construe such limitations as being directed to a “what” or a “how”. 

The Notice also states that in cases where “how” elements, including dosage schedules or dosage regimens, are deemed to be non-essential, their “mere recitation” in a claim “does not necessarily mean the claim is non-statutory”.

Although not specifically addressed by the Notice, use claims directed to a series of specific dosages would appear to be allowable, as such claims arguably recite limitations directed to a number of vendible products (a “what” rather than a “how”). Given that there are no additional claim fees in Canada, one appropriate response to the Notice may be to dissect such dosage range claims, thereby claiming uses of a series of discrete dosages.

With respect to claim limitations to a patient sub-population or site of administration, the Notice does not specifically address how such limitations, if worded in passive form (eg. “for administration to a site”), should be construed.  It is possible that such limitations, if appropriately worded, may be construed as directing the “what”, rather than the “how”, and may thus be allowable in view of the Notice. 


The Notice represents the latest of several steps taken by CIPO in its ongoing attempt to clarify Canadian Patent Office practice where the patentability of claimed subject matter relating to medical uses is at issue. This guidance started with the re-working of section 13.05.03 of the Manual of Patent Office Practice in 2009, which was effectively rescinded in part by Practice Notice PN2011-04, published in 2011, which in turn has been explicitly rescinded by the March 18, 2013 “Practice Guidance Following the Amazon FCA Decision”.

Whether the Notice is successful in this regard will likely depend upon how it is ultimately applied by examiners. In this respect, it may be appropriate to consider the following passage from the Federal Court of Appeal’s decision in Amazon:

Anyone who undertakes a purposive construction of a patent must do so on the basis of a foundation of knowledge about the relevant art, and in particular about the state of the relevant art at the relevant time. For the Commissioner [represented during patent prosecution by the examiner], that assistance comes in the form of submissions from the patent applicant and, I assume, from staff at the patent office with the appropriate experience. [Emphasis added.]

In this spirit, if CIPO encourages examiners to solicit and consider the assistance of patent applicants during prosecution with respect to, among other things, the critical step of purposive construction, the Notice may well achieve its stated goal of ensuring “efficient, predictable and reproducible examination” of medical use claims.