This decision underscores the importance of filing proper
disclaimers to patent claims. Disclaimers may be filed with the
patent office by a patentee after the issuance of a patent to
unilaterally renounce or disclaim those portions of the claimed
invention that were inadvertently included within the scope of the
claims as a result of mistake, accident or inadvertence.
Disclaimers therefore have the effect of narrowing the scope of the
claims (i.e. the area where competitors may not tread). Disclaimers
that attempt to broaden the scope of a claim are invalid.
In the present case, soon after the issuance on October 5, 1999
of Canadian patent number 2,169,670 (the '670 patent) relating
to telephone line couplers used to connect electronic equipment to
phone lines while providing electrical isolation, the appellant
patentee Paradox Security Systems Ltd. (Paradox) sent a demand
letter to the respondent Tyco Safety Products Canada Ltd. (Tyco)
alleging patent infringement. Tyco denied all allegations of
infringement and asserted that the '670 patent was invalid. On
October 6, 2003, Paradox filed a disclaimer to certain claims.
Much time at trial before the Federal Court was devoted to
whether the disclaimer actually had the effect of adding new
inventive elements to the patent claims, and thereby improperly
broadening the scope of the claims. The Court found that the
disclaimer did add new inventive elements, and that the disclaimer
was therefore invalid. Further, the Court found that the appellants
failed to establish that they had sought the disclaimer as a result
of "mistake, accident or inadvertence" and so the
disclaimer was found to be invalid on that ground too. Moreover, by
filing the disclaimer to the '670 patent, the patentee was in
effect conceding that their original patent was too broad in scope,
and therefore invalid as issued. Since the disclaimer was held to
be invalid, the Court dismissed the appellant's action for
patent infringement, and declared the '670 patent to be
The plaintiffs appealed to the Federal Court of Appeal, but the
lower court's ruling was upheld. The Court stated the following
which should be heeded by patentees:
"[T]he Federal Court has found that the disclaimer, by
broadening the original claims in the patent, is invalid. Were it
otherwise, parties could use disclaimers to broaden their patents
and obtain increased rights of exclusivity over those elements,
thereby changing the overall bargain and circumventing the
oversight of the Patent Office ...
There is a distinction between inventive elements and essential
elements. In a disclaimer, one cannot add inventive elements, as
that will broaden the scope of the patent. But adding essential
elements can narrow the scope of the patent ... the more essential
elements there are in the patent's claims, the narrower they
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 Mondaq.com.
Click to Login as an existing user or Register so you can print this article.
The Federal Court dismissed a motion by Apotex seeking particulars from Allergan's pleading relating to the prior art, inventive concept, promised utility and sound prediction of utility of the patents at issue.
Last year we saw the Canadian Courts release trademark decisions that granted a rare interlocutory injunction, issued jailed sentences for failure to comply with injunctive relief, grappled with trademark and internet issues...
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).