Patentability Of Methods Of Medical Treatment In Canada

A method of medical treatment is not patentable in Canada. This rule arises out of a concern that granting a monopoly over a method of medically treating a patient could interfere with physicians' skill and judgment when treating patients.1

Method versus Use

In contrast to claims for a method of medical treatment, a claim for a use of a compound or device to medically treat a disorder may be valid, so long as the claim does not limit the skill and judgment of a physician. For example, the following claim is considered to be patent-eligible subject matter in Canada:

1. The use of compound X to treat disorder Y.2

   The above claim goes to the use of a vendible product (i.e. compound X) to treat disorder Y and does not encompass any exercise of discretion by a physician during treatment. Instead, any decision of the physician to prescribe compound X properly lies outside of the scope of the claim.

   Contrast claim 1 above with claim 2, which is invalid as a method of medical treatment:

2. Use of compound X to treat disorder Y in a range of 13 to 15 mg/kg/day.3

   Claim 2 may be considered to encompass the skill and judgment of a physician, who is required to decide upon an appropriate dosage of compound X from the claimed dosage range when treating a patient having disorder Y.

   Where a claim such as claim 2 formally recites a "use", but in substance incorporates within its scope the skill and judgment of a physician, courts have held the claim to be invalid as a method of medical treatment. Additionally, if a claim includes one or more specific or implied steps (i.e. "how" to implement the use), then it may no longer be considered a "use" claim.4 Therefore, reciting "use" language in the preamble of a claim will not be determinative of patentability. One must instead construe the full scope of the claim to determine whether it impinges on a physician's discretion and may be considered a method of medical treatment.

   Various Canadian court decisions have applied the above-outlined distinction between valid use claims and invalid method claims for medical treatments. Figure 1 highlights some of these cases. Short summaries and links to full decisions can be viewed by clicking on the respective numerical indicators in the figure.

   *One of the claims at issue in decision 10 was determined to be for a use, while the other claims were determined to be for a method of medical treatment.

   Figure 1. Decisions distinguishing between method and use claims. All decisions deal with a medical treatment of a patient (represented by left circle). Method claims (represented by right circle) are not patentable, while use claims are patentable.

   Medical Treatment versus Non-Medical Treatment

   Of course, a claim is not invalid simply because it recites a method instead of a use. A method claim is invalid as a method of medical treatment if it includes a step of medical treatment (i.e., medical prevention, medical treatment or surgery).5 Method claims which in substance define non-medical treatments or manipulations such as a method of cosmetic treatment6 or a diagnostic method7 are valid. Claims for a method of treating a natural condition (as opposed to a pathological condition) such as aging8 or pregnancy9 are also valid, as are claims for methods of manipulating animals for economic benefit.10

   Similar to the method versus use distinction, one must look to the substance of the claim when determining whether a method claim is for a medical treatment. For example, in one case the Federal Court of Appeal found that the claimed "method of cleaning dental plaque or stains" included both a cosmetic treatment (i.e., cleaning teeth) and a medical treatment (i.e., reduction of the incidence of caries and/or periodontal disease). The claim was held invalid for including within its scope a method of medical treatment.11

   Figure 2 highlights decisions distinguishing between claims for methods of medical treatment and claims for methods of non-medical treatment. Short summaries and links to full decisions can be viewed by clicking on the respective numerical indicators in the figure.

   Figure 2. Decisions distinguishing between method claims for medical treatments and non-medical treatments. All decisions deal with method claims (represented by right circle). Medical treatments (represented by left circle) are not patentable, while non-medical treatments are patentable.

   Figure 3. Figures 1 and 2 combined. The left circle encompasses claims for...