Canadian Patent Practice: Written Description and Enablement


The Canadian Patent Act and Rules require that the specification correctly and fully describes and enables an invention, to allow the skilled person to put the invention into practice. Although external documents may be referred to in the description, the description itself has to disclose the nature of the claimed invention and it has to provide any teachings necessary to allow a person skilled in the art to operate the claimed invention. The level of description necessary will depend on the facts of each case. In general, where aspects of common general knowledge are referred to, it may not be necessary to do more than identify a well-known element or technique. Where specific information is required that does not form part of the common general knowledge, this must be explicitly provided. Furthermore, the specification should establish the utility of the invention, either by demonstration or sound prediction. The threshold that must be proven to establish utility is generally quite low; a “mere scintilla” of utility will suffice.

With respect to inventions in the field of biotechnology there are several additional considerations with regard to written description and enablement, which are briefly discussed below:


Generally, a claim to an antibody specific for an antigen will be considered to be supported by the specification provided: a) that the antibody has been prepared, or b) where an antibody has not be prepared, that the target antigen has been fully characterized, and there is no indication that the antibody might not be produced. Therefore, claims to an antibody specific for a novel antigen can be obtained even in the absence of working examples, provided the antigen has been fully characterized (for example by amino acid sequence, formula, chemical name, physical properties or by biological deposit).

For a new antibody to a known antigen, disclosure of a specifically recognized novel epitope or structural feature of the antibody (such as the set of complementarity determining region (CDR) sequences) may be required. The Canadian Patent Office takes the position that small changes to CDR sequences may significantly and unpredictably alter binding specificity and affinity and therefore the Patent Office will generally limit the scope to the exemplified CDR sequences.

Biological Deposits

Biological Deposits may be taken into account in determining whether a specification complies with the description and enablement requirements. Where the invention cannot be enabled in the absence of access to a biological material, the deposit is a necessary element to make the description sufficient unless the required material is publicly known and reliably available.

Sequence Listing

Adequate description of a biopolymer such as nucleotide or amino acid sequence must be disclosed in the specification in order for the biopolymer to be patentable. The application must contain a sequence listing in electronic form if the specification discloses a nucleotide or amino acid sequence, other than one that belongs to the prior art.

Different jurisdictions have different support and enablement requirements. Familiarity with these requirements is not only valuable when preparing international applications, but also when prosecuting applications in multiple jurisdictions. We advise clients on the nuances governing disclosure requirements and that are relevant for the claim scope that might be obtained and successfully defended in Canada.



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