Canada: Canadian Patent Office Issues Practice Notice Regarding Signal Claims

Last Updated: December 13 2007

Article by Brett Slaney © 2007, Blake, Cassels & Graydon LLP

Originally published in Blakes Bulletin on Intellectual Property, December 2007

With the proliferation of information technology and most notably Internet-based activity, it is becoming increasingly difficult in the field of electromagnetic and acoustic signals (signals) to enforce patent rights, particularly when there are several entities in different jurisdictions performing the patented method or each providing only a piece of a patented system.

This can lead to situations where the only way to enforce a patent in a given jurisdiction is to pursue many individuals, such as consumers, who download patent-infringing software over the Internet. It is therefore desirable to protect the invention embodied in a transient signal or carrier wave since that may be the only tangible form of the invention that exists in a particular jurisdiction.

On August 14, 2007 the Canadian Patent Office (the Office) published an Office Practice Notice (the Notice) to formally express its position regarding the patentability of signals. Pursuant to the Notice, the Office deems signals to be forms of energy and thus, "do not contain matter even though the signal may be transmitted through a physical medium." Consequently, any claims to signals per se do not constitute statutory subject matter within the meaning of the definition of "invention" in section 2 of the Patent Act.

Section 2 of the Patent Act defines "invention" as being any new and useful art, process, machine, manufacture or composition of matter, or any new and useful improvement in any art, process, machine, manufacture or composition of matter. In the Notice, the Office attempts to clarify its position that signals do not fall within any of these categories as follows:

More particularly, an electromagnetic or acoustic signal is interpreted to be neither an "art" nor a "process" because it is not an act or series of acts or method of operation by which a result or effect is produced by physical or chemical action. Neither is an electromagnetic or acoustic signal a "machine" as it is not the mechanical embodiment of any function or mode of operation, designed to accomplish a particular effect, or a "composition of matter", as it is not a chemical compound, composition or substance. An electromagnetic or acoustic signal is taken not to be itself a material product and, therefore, not a "manufacture".

The Office explains its position only pertains to signals per se and does not apply to methods, processes, machines or manufactures involved in the generation, transmission, reception or processing of signals. The Notice was effective immediately (i.e., as of August 14, 2007) and superseded any previously communicated practices related to the patentability of signals.

The Office’s analysis does not appear to be consistent with the Supreme Court of Canada’s interpretation of "art" as set out in Shell Oil Co. v. The Commissioner of Patents. In Shell Oil, the Supreme Court reviewed the criteria for patentable subject matter, reviewed its earlier decision of Tennessee Eastman and Lawson v. The Commissioner of Patents and provided a broad interpretation of the term "art". Also, in Tennessee Eastman, the Court affirmed that "art" was a word of very wide connotation and was not to be confined to new processes or products or manufacturing techniques, but should be extended to new methods of applying skill or knowledge provided that they produce effects or results commercially useful to the public. It would seem that this reasoning should extend to including a signal as patentable subject matter since the use of a signal with particular characteristics produces a commercially useful effect.

What Does The Notice Mean To Applicants And Practitioners?

The Notice is only a guideline for examiners, applicants and practitioners, and neither the Patent Act nor the Patent Rules have been amended to exclude claims to signals per se. Therefore, there is still an opportunity to argue in favour of a signal claim that is rejected by an examiner during substantive examination, especially given the inconsistencies between the Notice and the established case law. Meanwhile, however, we can expect the examiners to follow the Notice and issue rejections accordingly. This will affect not only cases filed after August 14, 2007, but also pending applications filed prior to that date that have not yet been examined.

The Office’s position appears to essentially echo the United States Patent and Trademark Office’s (USPTO) position in In re Nuijten, which was recently affirmed on appeal. Nuijten was attempting to patent claims covering the introduction of "watermarks" into signals. The claim in question was directed to: "A signal with embedded supplemental data, the signal being encoded in accordance with a given encoding process...", i.e., there was some context and specific claim language to consider. The USPTO and the Court of Appeals for the Federal Circuit provided a detailed analysis as to whether a signal was a "manufacture", ultimately deciding that a signal is not a "manufacture" under U.S. law. Rather than address this issue within a specific context, the Office seems to have instead imported the USPTO’s position into Canadian practice without any such specific context, let alone a careful analysis of all the issues resulting from the exclusion of these types of claims. Moreover, as noted above, the brief analysis provided in the Notice appears to be inconsistent with established Canadian case law.

The Office is clearly against granting patent protection for an invention embodied as a signal but it has not clarified whether or not (or how) what is carried by the signal would be protected by another type of claim. There is no indication that a claim for a signal carrying a set of instructions or a data structure, that would otherwise be patentable in a different form, e.g., by a computer-readable medium claim, would be allowed. This could be an issue where an infringer facilitates the transmission of the set of patentable instructions or data structure carried by the signal, but does not actually store all of the instructions or data structure together at the same time. Would a patentee be able to stop an infringer in Canada that does not store such patentable instructions together at the same time but merely relays them in portions carried by a signal to another entity outside of Canada? The Notice does not give us any clarification on the practical implications of such a widereaching exclusion.

Unfortunately, in the end, the Office has made it clear that it believes signals per se should not be patentable without providing any context and very little explanation. For now, an applicant filing a patent application in Canada should be aware that signal claims per se will surely be rejected by the examiner as being non-statutory subject matter. However, as has been observed in the software context, the Patent Appeal Board often overturns examiners’ decisions involving an overly conservative approach to determining patentable subject matter.

The content of this article is intended to provide a general guide to the subject matter. Specialist advice should be sought about your specific circumstances.

To print this article, all you need is to be registered on

Click to Login as an existing user or Register so you can print this article.

Events from this Firm
27 Oct 2016, Seminar, Toronto, Canada

Please join members of the Blakes Commercial Real Estate group as they discuss five key provisions of a commercial real estate purchase agreement that are often the subject of much negotiation but are sometimes misunderstood.

1 Nov 2016, Seminar, Toronto, Canada

What is the emotional culture of your organization?

Every organization and workplace has an emotional culture that can have an impact on everything from employee performance to customer or client satisfaction.

3 Nov 2016, Seminar, Toronto, Canada

Join leading lawyers from the Blakes Pensions, Benefits & Executive Compensation group as they discuss recent updates and legal developments in pension and employee benefits law as well as strategies to identify and minimize common risks.

In association with
Related Video
Up-coming Events Search
Font Size:
Mondaq on Twitter
Register for Access and our Free Biweekly Alert for
This service is completely free. Access 250,000 archived articles from 100+ countries and get a personalised email twice a week covering developments (and yes, our lawyers like to think you’ve read our Disclaimer).
Email Address
Company Name
Confirm Password
Mondaq Topics -- Select your Interests
 Law Performance
 Law Practice
 Media & IT
 Real Estate
 Wealth Mgt
Asia Pacific
European Union
Latin America
Middle East
United States
Worldwide Updates
Check to state you have read and
agree to our Terms and Conditions

Terms & Conditions and Privacy Statement (the Website) is owned and managed by Mondaq Ltd and as a user you are granted a non-exclusive, revocable license to access the Website under its terms and conditions of use. Your use of the Website constitutes your agreement to the following terms and conditions of use. Mondaq Ltd may terminate your use of the Website if you are in breach of these terms and conditions or if Mondaq Ltd decides to terminate your license of use for whatever reason.

Use of

You may use the Website but are required to register as a user if you wish to read the full text of the content and articles available (the Content). You may not modify, publish, transmit, transfer or sell, reproduce, create derivative works from, distribute, perform, link, display, or in any way exploit any of the Content, in whole or in part, except as expressly permitted in these terms & conditions or with the prior written consent of Mondaq Ltd. You may not use electronic or other means to extract details or information about’s content, users or contributors in order to offer them any services or products which compete directly or indirectly with Mondaq Ltd’s services and products.


Mondaq Ltd and/or its respective suppliers make no representations about the suitability of the information contained in the documents and related graphics published on this server for any purpose. All such documents and related graphics are provided "as is" without warranty of any kind. Mondaq Ltd and/or its respective suppliers hereby disclaim all warranties and conditions with regard to this information, including all implied warranties and conditions of merchantability, fitness for a particular purpose, title and non-infringement. In no event shall Mondaq Ltd and/or its respective suppliers be liable for any special, indirect or consequential damages or any damages whatsoever resulting from loss of use, data or profits, whether in an action of contract, negligence or other tortious action, arising out of or in connection with the use or performance of information available from this server.

The documents and related graphics published on this server could include technical inaccuracies or typographical errors. Changes are periodically added to the information herein. Mondaq Ltd and/or its respective suppliers may make improvements and/or changes in the product(s) and/or the program(s) described herein at any time.


Mondaq Ltd requires you to register and provide information that personally identifies you, including what sort of information you are interested in, for three primary purposes:

  • To allow you to personalize the Mondaq websites you are visiting.
  • To enable features such as password reminder, newsletter alerts, email a colleague, and linking from Mondaq (and its affiliate sites) to your website.
  • To produce demographic feedback for our information providers who provide information free for your use.

Mondaq (and its affiliate sites) do not sell or provide your details to third parties other than information providers. The reason we provide our information providers with this information is so that they can measure the response their articles are receiving and provide you with information about their products and services.

If you do not want us to provide your name and email address you may opt out by clicking here .

If you do not wish to receive any future announcements of products and services offered by Mondaq by clicking here .

Information Collection and Use

We require site users to register with Mondaq (and its affiliate sites) to view the free information on the site. We also collect information from our users at several different points on the websites: this is so that we can customise the sites according to individual usage, provide 'session-aware' functionality, and ensure that content is acquired and developed appropriately. This gives us an overall picture of our user profiles, which in turn shows to our Editorial Contributors the type of person they are reaching by posting articles on Mondaq (and its affiliate sites) – meaning more free content for registered users.

We are only able to provide the material on the Mondaq (and its affiliate sites) site free to site visitors because we can pass on information about the pages that users are viewing and the personal information users provide to us (e.g. email addresses) to reputable contributing firms such as law firms who author those pages. We do not sell or rent information to anyone else other than the authors of those pages, who may change from time to time. Should you wish us not to disclose your details to any of these parties, please tick the box above or tick the box marked "Opt out of Registration Information Disclosure" on the Your Profile page. We and our author organisations may only contact you via email or other means if you allow us to do so. Users can opt out of contact when they register on the site, or send an email to with “no disclosure” in the subject heading

Mondaq News Alerts

In order to receive Mondaq News Alerts, users have to complete a separate registration form. This is a personalised service where users choose regions and topics of interest and we send it only to those users who have requested it. Users can stop receiving these Alerts by going to the Mondaq News Alerts page and deselecting all interest areas. In the same way users can amend their personal preferences to add or remove subject areas.


A cookie is a small text file written to a user’s hard drive that contains an identifying user number. The cookies do not contain any personal information about users. We use the cookie so users do not have to log in every time they use the service and the cookie will automatically expire if you do not visit the Mondaq website (or its affiliate sites) for 12 months. We also use the cookie to personalise a user's experience of the site (for example to show information specific to a user's region). As the Mondaq sites are fully personalised and cookies are essential to its core technology the site will function unpredictably with browsers that do not support cookies - or where cookies are disabled (in these circumstances we advise you to attempt to locate the information you require elsewhere on the web). However if you are concerned about the presence of a Mondaq cookie on your machine you can also choose to expire the cookie immediately (remove it) by selecting the 'Log Off' menu option as the last thing you do when you use the site.

Some of our business partners may use cookies on our site (for example, advertisers). However, we have no access to or control over these cookies and we are not aware of any at present that do so.

Log Files

We use IP addresses to analyse trends, administer the site, track movement, and gather broad demographic information for aggregate use. IP addresses are not linked to personally identifiable information.


This web site contains links to other sites. Please be aware that Mondaq (or its affiliate sites) are not responsible for the privacy practices of such other sites. We encourage our users to be aware when they leave our site and to read the privacy statements of these third party sites. This privacy statement applies solely to information collected by this Web site.

Surveys & Contests

From time-to-time our site requests information from users via surveys or contests. Participation in these surveys or contests is completely voluntary and the user therefore has a choice whether or not to disclose any information requested. Information requested may include contact information (such as name and delivery address), and demographic information (such as postcode, age level). Contact information will be used to notify the winners and award prizes. Survey information will be used for purposes of monitoring or improving the functionality of the site.


If a user elects to use our referral service for informing a friend about our site, we ask them for the friend’s name and email address. Mondaq stores this information and may contact the friend to invite them to register with Mondaq, but they will not be contacted more than once. The friend may contact Mondaq to request the removal of this information from our database.


This website takes every reasonable precaution to protect our users’ information. When users submit sensitive information via the website, your information is protected using firewalls and other security technology. If you have any questions about the security at our website, you can send an email to

Correcting/Updating Personal Information

If a user’s personally identifiable information changes (such as postcode), or if a user no longer desires our service, we will endeavour to provide a way to correct, update or remove that user’s personal data provided to us. This can usually be done at the “Your Profile” page or by sending an email to

Notification of Changes

If we decide to change our Terms & Conditions or Privacy Policy, we will post those changes on our site so our users are always aware of what information we collect, how we use it, and under what circumstances, if any, we disclose it. If at any point we decide to use personally identifiable information in a manner different from that stated at the time it was collected, we will notify users by way of an email. Users will have a choice as to whether or not we use their information in this different manner. We will use information in accordance with the privacy policy under which the information was collected.

How to contact Mondaq

You can contact us with comments or queries at

If for some reason you believe Mondaq Ltd. has not adhered to these principles, please notify us by e-mail at and we will use commercially reasonable efforts to determine and correct the problem promptly.