Canada: Court Refuses to Extend Trade-mark Protection to File Extensions

Last Updated: May 27 2010
Article by Sharon S. Ho

Most Read Contributor in Canada, September 2018

In Autodesk, Inc. v. Dassault Systèmes Solidworks Corporation, the US District Court for the Northern District of California recently considered whether computer file extensions are entitled to trade-mark protection.

File extensions are the suffixes in computer file names, which generally comprise three or four characters. Their main purpose is to help computers identify the type of content that is in a computer file.

In this case, both parties produce software for 2D and 3D design and drafting. The plaintiff, Autodesk, Inc., produces a software product called AutoCAD, which uses files with the extension ".dwg." The defendant, Dassault, had released various products in association with its own trade-marks that incorporated the formative word element "DWG," and it marketed software that utilized or reverse-engineered the form of Autodesk's .dwg file format.

Autodesk sued Dassault for trade-mark infringement under the Lanham Act (the US trade-mark legislation) and a host of other causes of action including unfair competition, false designation of origin, unfair or deceptive business practices, and deceptive, false and misleading advertising. Autodesk claimed that Dassault had misappropriated Autodesk's mark, DWG. Dassault argued that DWG was functional or generic, and therefore not entitled to trade-mark protection. Both parties moved for summary judgment on various motions. One of the main issues before the court was whether Autodesk had a valid common law trade-mark in respect of DWG.

At the summary judgment motions, Autodesk explicitly disavowed any claims against the use of .dwg as a file extension and sought trade-mark protection for only its use as a word mark. Specifically, Autodesk confirmed that it was only seeking to have the exclusive use of DWG in packaging, advertising and marketing materials. Autodesk's counsel, at the hearing, even went so far as to admit to the court that "any one in the world has a right to use DWG as a file extension" and that some competitor products actually would save files as .dwg files to render those files interoperable with AutoCAD products.

In ruling on the motions, the court partially sided with Autodesk. The court found that, in addition to the functional use, Autodesk had used DWG in a non-functional way (for example, in its product names). Therefore, the mark was not invalid on the grounds of functionality. The judge noted that Autodesk had expressly disavowed any ownership of any functional use of DWG, including the use of DWG as a file extension. This disavowal appears to have weighed heavily in the court's decision to not find the DWG mark invalid for functional reasons.

After the court's decision was rendered on the motions, Autodesk attempted to qualify its disavowal, claiming that it had only disavowed uses of .dwg as a file extension when such uses were necessary to achieve interoperability with its DWG file format. The court issued a further ruling, refusing to let Autodesk qualify its disavowal. The court found that ownership of file extension designations cannot be appropriated under the Lanham Act — file extensions are inherently functional, and functional uses cannot be trade-marked. It stated that computer programmers and computer users should be free to designate file extensions as they see fit, without the fear of infringing trade-marks.

The motions judge further opined that the purpose of the Lanham Act is to target unauthorized use of a trade-mark "in connection with a commercial transaction in which the trade-mark is being used to confuse potential consumers." In contrast, the purpose of file extensions is to indicate to a computer the type of file that is being handled. The court noted that "a computer is not a consumer," and its recognition of a file extension is not "in connection with a commercial transaction." In other words, the computer does not concern itself with the question of who made the file format. Therefore, whether on the grounds that a file extension connotes a "functional use" or a "non-trade-mark use," the court held that a file extension per se is not protectable under US trade-mark law.

In its decision, the court did recognize that computer users may associate a particular file extension with a specific vendor or manufacturer. However, the court found this association only incidental to the primary function of file extensions, namely to identify a file or file type. On the question of whether DWG was generic, the court declined to address the issue on summary judgment as there were genuine issues of material fact involved.

On the eve of trial, the parties settled the dispute and, as part of the settlement, they also came to agreement that DWG is a valid trade-mark owned by Autodesk.

McCarthy Tétrault Notes

While the court found that there are no trade-mark rights enforceable in file extensions per se, the specific characters in a file extension may be protected as a word mark, for instance, for use in packaging, advertising and marketing materials of a corresponding software product.

In Canada, a recently allowed application by Autodesk, Inc. exists for the word mark DWG for use in association with "computer programs and software in the field of computer aided design and instruction manuals sold as a unit." It will be interesting to see how a Canadian court would rule on the issue if Autodesk were to assert its trade-mark rights against the use of .dwg as a file extension in Canada. The expectation is that a Canadian court would not protect DWG as a trade-mark when the mark is used as a file extension because the reverse would grant Autodesk Inc. a monopoly on functional elements of their wares, thus preventing others from creating computer files that could work with Autodesk Inc.'s software. This is consistent with the longstanding rule in Canada that anything that is primarily functional cannot be the subject of trade-mark protection.

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.

In association with
Related Topics
Related Articles
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
Registration (you must scroll down to set your data preferences)

Mondaq Ltd requires you to register and provide information that personally identifies you, including your content preferences, for three primary purposes (full details of Mondaq’s use of your personal data can be found in our Privacy and Cookies Notice):

  • To allow you to personalize the Mondaq websites you are visiting to show content ("Content") relevant to your interests.
  • To enable features such as password reminder, news alerts, email a colleague, and linking from Mondaq (and its affiliate sites) to your website.
  • To produce demographic feedback for our content providers ("Contributors") who contribute Content for free for your use.

Mondaq hopes that our registered users will support us in maintaining our free to view business model by consenting to our use of your personal data as described below.

Mondaq has a "free to view" business model. Our services are paid for by Contributors in exchange for Mondaq providing them with access to information about who accesses their content. Once personal data is transferred to our Contributors they become a data controller of this personal data. They use it to measure the response that their articles are receiving, as a form of market research. They may also use it to provide Mondaq users with information about their products and services.

Details of each Contributor to which your personal data will be transferred is clearly stated within the Content that you access. For full details of how this Contributor will use your personal data, you should review the Contributor’s own Privacy Notice.

Please indicate your preference below:

Yes, I am happy to support Mondaq in maintaining its free to view business model by agreeing to allow Mondaq to share my personal data with Contributors whose Content I access
No, I do not want Mondaq to share my personal data with Contributors

Also please let us know whether you are happy to receive communications promoting products and services offered by Mondaq:

Yes, I am happy to received promotional communications from Mondaq
No, please do not send me promotional communications from Mondaq
Terms & Conditions (the Website) is owned and managed by Mondaq Ltd (Mondaq). Mondaq grants you a non-exclusive, revocable licence to access the Website and associated services, such as the Mondaq News Alerts (Services), subject to and in consideration of your compliance with the following terms and conditions of use (Terms). Your use of the Website and/or Services constitutes your agreement to the Terms. Mondaq may terminate your use of the Website and Services if you are in breach of these Terms or if Mondaq decides to terminate the licence granted hereunder for any reason whatsoever.

Use of

To Use you must be: eighteen (18) years old or over; legally capable of entering into binding contracts; and not in any way prohibited by the applicable law to enter into these Terms in the jurisdiction which you are currently located.

You may use the Website as an unregistered user, however, you are required to register as a user if you wish to read the full text of the Content or to receive the Services.

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 or with the prior written consent of Mondaq. You may not use electronic or other means to extract details or information from the Content. Nor shall you extract information about users or Contributors in order to offer them any services or products.

In your use of the Website and/or Services you shall: comply with all applicable laws, regulations, directives and legislations which apply to your Use of the Website and/or Services in whatever country you are physically located including without limitation any and all consumer law, export control laws and regulations; provide to us true, correct and accurate information and promptly inform us in the event that any information that you have provided to us changes or becomes inaccurate; notify Mondaq immediately of any circumstances where you have reason to believe that any Intellectual Property Rights or any other rights of any third party may have been infringed; co-operate with reasonable security or other checks or requests for information made by Mondaq from time to time; and at all times be fully liable for the breach of any of these Terms by a third party using your login details to access the Website and/or Services

however, you shall not: do anything likely to impair, interfere with or damage or cause harm or distress to any persons, or the network; do anything that will infringe any Intellectual Property Rights or other rights of Mondaq or any third party; or use the Website, Services and/or Content otherwise than in accordance with these Terms; use any trade marks or service marks of Mondaq or the Contributors, or do anything which may be seen to take unfair advantage of the reputation and goodwill of Mondaq or the Contributors, or the Website, Services and/or Content.

Mondaq reserves the right, in its sole discretion, to take any action that it deems necessary and appropriate in the event it considers that there is a breach or threatened breach of the Terms.

Mondaq’s Rights and Obligations

Unless otherwise expressly set out to the contrary, nothing in these Terms shall serve to transfer from Mondaq to you, any Intellectual Property Rights owned by and/or licensed to Mondaq and all rights, title and interest in and to such Intellectual Property Rights will remain exclusively with Mondaq and/or its licensors.

Mondaq shall use its reasonable endeavours to make the Website and Services available to you at all times, but we cannot guarantee an uninterrupted and fault free service.

Mondaq reserves the right to make changes to the services and/or the Website or part thereof, from time to time, and we may add, remove, modify and/or vary any elements of features and functionalities of the Website or the services.

Mondaq also reserves the right from time to time to monitor your Use of the Website and/or services.


The Content is general information only. It is not intended to constitute legal advice or seek to be the complete and comprehensive statement of the law, nor is it intended to address your specific requirements or provide advice on which reliance should be placed. Mondaq and/or its Contributors and other suppliers make no representations about the suitability of the information contained in the Content for any purpose. All Content provided "as is" without warranty of any kind. Mondaq and/or its Contributors and other suppliers hereby exclude and disclaim all representations, warranties or guarantees with regard to the Content, including all implied warranties and conditions of merchantability, fitness for a particular purpose, title and non-infringement. To the maximum extent permitted by law, Mondaq expressly excludes all representations, warranties, obligations, and liabilities arising out of or in connection with all Content. In no event shall Mondaq 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 of the Content or performance of Mondaq’s Services.


Mondaq may alter or amend these Terms by amending them on the Website. By continuing to Use the Services and/or the Website after such amendment, you will be deemed to have accepted any amendment to these Terms.

These Terms shall be governed by and construed in accordance with the laws of England and Wales and you irrevocably submit to the exclusive jurisdiction of the courts of England and Wales to settle any dispute which may arise out of or in connection with these Terms. If you live outside the United Kingdom, English law shall apply only to the extent that English law shall not deprive you of any legal protection accorded in accordance with the law of the place where you are habitually resident ("Local Law"). In the event English law deprives you of any legal protection which is accorded to you under Local Law, then these terms shall be governed by Local Law and any dispute or claim arising out of or in connection with these Terms shall be subject to the non-exclusive jurisdiction of the courts where you are habitually resident.

You may print and keep a copy of these Terms, which form the entire agreement between you and Mondaq and supersede any other communications or advertising in respect of the Service and/or the Website.

No delay in exercising or non-exercise by you and/or Mondaq of any of its rights under or in connection with these Terms shall operate as a waiver or release of each of your or Mondaq’s right. Rather, any such waiver or release must be specifically granted in writing signed by the party granting it.

If any part of these Terms is held unenforceable, that part shall be enforced to the maximum extent permissible so as to give effect to the intent of the parties, and the Terms shall continue in full force and effect.

Mondaq shall not incur any liability to you on account of any loss or damage resulting from any delay or failure to perform all or any part of these Terms if such delay or failure is caused, in whole or in part, by events, occurrences, or causes beyond the control of Mondaq. Such events, occurrences or causes will include, without limitation, acts of God, strikes, lockouts, server and network failure, riots, acts of war, earthquakes, fire and explosions.

By clicking Register you state you have read and agree to our Terms and Conditions