The use of clear and concise language is required when drafting claims for a Canadian patent application. Although imprecise terms should be avoided, “or” and “and/or” terms are (increasingly) included to avoid excess claim fees, working to reduce the total number of claims below 20.

Section 16.03.02 of MOPOP states that “or” and “and/or” terms may be used in an indefinite manner “in certain circumstances.” Other occasionally indefinite terms include: “containing as an active ingredient,” “therapeutically effective amount,” “a major part,” “of the character described” or “as herein described,” “at least” or “at least one of,” “an effective amount” or “a sufficient amount” or “a synergistic amount,” and “not being…” or “not having…” or “not requiring.” There is a lack of guidance for what “certain circumstances” entails and what may result in an indefinite objection under subsection 27(4) of the Patent Act. As a result, the reasoning behind receiving such an objection may be left to the Canadian examiner’s individual discretion.

Considerations should be made for what the use of “or” and “and/or” implies once included in a claim. Using “or” is generally allowed by examiners, given that it is often used to list two or more variables, making the claim specific. Using “and/or” implies that there are two or more possible variables, which can lead to examiners to believe that the claim is ambiguous.

The use of “or” to recite alternatives in a claim could pose issues during litigation. If one of the alternatives is unpatentable, then the claim as a whole may be invalidated, as decided by the Court in Abbott Laboratories v. Canada (Minister of Health), 2005 FC 1332.

Including “or” and “and/or” terms in patent claims may be useful to avoid excess claim fees. If the number of claims exceeds 20 during the prosecution of a patent application, excess claims will be payable when paying the final fee (even if the number of claims ultimately issued is 20 or fewer). However, drafters should understand the possibility of receiving indefinite objections or risks of having entire claims invalidated in the future.


This article is provided for informational purposes only and is not legal advice. For further information, please contact us by phone (416) 847-0054 or by email at