Canada’s Intellectual Property Firm

Reinventing the wheel, and other patents for improvements

Authored byJonas Gifford

In 2011, Canadian Patent No. 2,618,502 was granted to the Honda Motor Co., Ltd., for an invention titled "Vehicle Wheel." Of course, the claims in this patent could not possibly cover all vehicle wheels because many vehicle wheels existed long before this invention was made. Rather, the claims in this patent recite certain features, such as spokes having hollow portions with water discharge holes, and the Canadian Patent Office accepted that the claims of this patent were inventive over the many vehicle wheels that could be considered prior art.

The Honda patent is but one example of patents that may be granted for improvements to certain subject matter, even where that subject matter is very well known. In fact, sometimes a valid patent can be issued where the only change in the subject matter is how a known substance may be used.

For example, azidothymidine is a chemical compound that was first synthesized in 1964 in an effort to treat cancer using anti-retroviral drugs. The anti-retroviral approach to cancer treatment was eventually considered unsuccessful, and azidothymidine was shelved. Years later, however, anti-retroviral drugs proved effective to treat human immunodeficiency virus ("HIV") and acquired immune deficiency syndrome ("AIDS"). Azidothymidine, now often known as AZT, was a major breakthrough for treating these fatal diseases. In 2002, the Supreme Court of Canada upheld patent claims for the use of AZT to treat HIV and AIDS, even though AZT had been a known compound.

As these examples illustrate, patentable inventions do not need to be completely new. Rather, a patent for an improvement may be valid — and in some cases very valuable — if the claims of the patent adequately define an invention. To do so, the claims must define a scope of subject matter that is new and that would not be obvious in view of the relevant prior art.

The Supreme Court of Canada most recently considered obviousness in the 2008 decision Apotex Inc. v. Sanofi-Synthelabo Canada Inc., which involved pharmaceutical subject matter. In this decision, the Court confirmed that a patentable invention may be based on a new invention such as a new reaction or compound, or on a selection of some of a set of known compounds. In this particular decision, the Court found that clopidogrel bisulfate, also known as PLAVIX, was patentable as a selection from a set of some 250,000 compounds that were already known, because clopidogrel bisulfate had special advantages over the other compounds in the known set.

Although the Sanofi decision involved pharmaceutical subject matter, the principles from this decision are widely applicable to numerous fields. For example, in mechanical inventions such as vehicle wheels, the separate pieces of a wheel may all be known, but a particular combination of these pieces may be patentable if such a combination is not obvious in view of the relevant prior art.

According to the Sanofi decision, the question of obviousness is largely concerned with how a skilled worker would have acted in light of the prior art. If the prior art would not have led a skilled worker to a particular selection or combination, then the selection or the combination may be patentable. Therefore, inventors of such improvements to known subject matter should consider seeking professional advice regarding pursuing patent protection for such improvements.


The preceding is intended as a timely update on Canadian intellectual property and technology law. The content is informational only and does not constitute legal or professional advice. To obtain such advice, please communicate with our offices directly.