Occasionally, a third party may wish to dispute the patentability of a pending patent application or the validity of an issued patent. However, in Canada, there is no post-patent-grant opposition procedure, such as is available before the European Patent Office. Nevertheless, alternatives to costly judicial proceedings are available.

Filing Prior Art / Protests

Before the grant of a patent, any person, including a third party unrelated to the patent applicant, may file prior art with the Patent Office or otherwise protest against a pending patent application or any of its claims.

Prior art includes patents, published patent applications, or any other printed publications that may have a bearing on the patentability of any claim in a patent application. In addition, an explanation as to the pertinency of the prior art is required. It should be noted that pertinency is not limited to allegations of lack of novelty or obviousness, but may help to substantiate other grounds affecting patentability, such as insufficient description or support. Should a foreign language publication be submitted, a translation of the publication into English or French is advisable.

A protest can extend beyond the mere submission of prior art and can include submissions questioning patentability on a variety of grounds. Allegations such as inoperability, improper amendment to add new subject matter or any other ground for non-compliance with the Patent Act or Patent Rules may be raised.

The filing of prior art or protest may be used as a means to put before an examiner printed publications or other information that might not be identified in a routine search during examination. For example, in Canadian Patent Application No. 2,166,001, Decision No. 1263, dated July 13, 2005 (Comm'r Pat.), a product monograph, a United States Federal District Court Memorandum of Opinion and Order, and excerpts of trial transcripts from Canadian Federal Court proceedings were introduced in a protest and considered by the examiner.

Such filings may also be a means to prompt the examiner to more carefully consider the question of patentability or other grounds of non-compliance or may lead to the identification of additional relevant documentation.

Affidavits may also be submitted, not only to introduce additional documentation but also to provide additional information that may be helpful in considering the question of patentability. For example, an affidavit may provide relevant information concerning the technology or state of the art, set out background circumstances or events, or characterize the person of skill in the art.

The prior art or protest may be submitted before, during or after the examination process. If submitted before, the submission will not be considered by the patent examiner until after the request for examination is received. The information in the submission will be taken into account by the examiner during examination. If sufficient grounds for objection are raised, the submission will be cited by the patent examiner.

The protest or prior art may also be submitted after a notice of allowance has been issued, but before a patent has been granted. If the protest or prior art raises matters such that the Commissioner has reasonable grounds to believe that the application does not comply with the Patent Act or Patent Rules, the notice of allowance may be withdrawn and the application returned to the examiner for further examination.

However, a third party's participation is limited. The third party's submission concerning prior art or protest is acknowledged by the Patent Office but no further information will be given as to action taken. Accordingly, the third party will be required to independently monitor the patent file to determine the outcome. The third party has no right of appeal if the patent is granted.

The chance of success is dependent upon the strength of the written submissions and the particular matters raised. The examiner may or may not be persuaded that the matters raised affect the patentability of a patent claim. In the event that the examiner cites the prior art or matters raised in the protest, the patent applicant nevertheless has the right to respond, including by argument or by amendment to the patent specification. The examiner may ultimately refuse to allow the patent application or a patent may issue with narrower patent claims. The patent may ultimately issue without any change in claim scope but following a longer examination process.

On the other hand, there are no government fees associated with the submission of a protest or the filing of prior art. The submissions may prompt the examiner to delay allowance, to take additional steps such as conducting a further search for prior art, or to issue a further Office Action. The submissions may lead to the discovery of additional prior art, provide additional grounds for objection, or identify contraventions of the Patent Act and Rules. This mechanism also provides a means for a third party to publicly dispute validity or patentability of a patent application in a manner that is associated with the file wrapper of a patent application.

The Federal Court has stated that a protest is a remedy that ought to be exhausted before a third party can seek judicial review of a Commissioner's decision to allow a patent application.


Once a patent is issued, any person, including a third party unconnected with the patentee, may request re-examination of one or more patent claims by filing prior art with the Commissioner of Patents. The prior art may only consist of patents, published patent applications, and printed publications. A submission setting out the pertinency of the prior art and how it is to be applied against the claims is to be included in the request. A request for re-examination may be submitted at any time during the life of the patent. However, there is a government fee of $2500 Cdn to file the request.

Once a request is received, notice is provided to the patentee and a re-examination board is set up by the Commissioner of Patents. Typically, the re-examination board will consist of two examiners and one member of the Patent Appeal Board. The initial examiner from the application stage is generally not included on the board.

The re-examination board must determine that there is a substantial new question of patentability affecting any claim for re-examination to occur. In the case of a refusal by the re-examination board, notification will be provided to the third-party requestor. The requestor has no right of appeal.

Should re-examination be warranted, the patentee will be notified and provided with a right to reply to the request. The patentee may propose any amendment to the patent claims but cannot enlarge claim scope. A third-party requestor has no further role in the re-examination process. Should a third-party requestor provide submissions at this stage, typically, these submissions are not considered.

The scope of re-examination is quite narrow. The re-examination board will only consider the claim(s) in question against the supplied prior art. The board has the power to cancel one or more claims, to confirm that any claim is patentable, or to incorporate any amendment or new claim into a patent. The board cannot make any amendments to the description and will not consider any matter beyond the claims in question and the prior art submitted. The patentee has a right of appeal.

Re-examination provides a more summary, expedient, low-cost means for having the validity of patent claims considered against previously undiscovered prior art.

Judicial Proceedings

In the event that a protest or re-examination proceeding fails, a third party may still commence a judicial proceeding in the Federal Court seeking a declaration that an issued patent or any claim is invalid or void. In such a case, the third party may allege all matters of invalidity of a patent, conduct discovery and have a full trial before a judge.

In Canada, a party must have standing to commence such proceedings. The party has standing if it is established that it is an "interested person." This threshold is low - a party is sufficiently "interested" if it is able to show that it is engaged in dealing with the same kind of thing as the patentee and is in competition with it. There is no need to establish an actual case or controversy and thus there is no need for an infringement proceeding or threatened infringement proceeding to be shown for a third party to have standing to start legal proceedings.


Even without the availability of opposition proceedings in Canada, there are low-cost procedural mechanisms available for a third party to dispute a patent grant or the scope of patent claims. Although a third party's role may be limited, cancellation or narrowing of one or more patent claims may result. In any event, procedural or strategic advantages may flow from such proceedings. Such procedural avenues ought to be considered before embarking upon more costly patent impeachment proceedings, which nevertheless remain an available option.