2021-07-06
When filing more than one patent application that relates to the same technology, the potential issue of double patenting can arise. While double patenting can occur in both Canada and the United States, the ways in which it is dealt with in each country is significantly different.
In Whirlpool Corp. v Camco Inc., the Supreme Court of Canada held that there are two branches of prohibitions against double patenting—the first related to "same invention" or "co-terminus," double patenting, and the second related to "obviousness" double patenting. The reason that double patenting is prohibited is to prevent people from obtaining more than one patent for the same invention, known as evergreening. In Canada, a patent is valid for up to 20 years and after its expiry, the invention can be used by anyone in the public without the potential for infringement. If a patent owner was able to obtain a second patent for the same invention, they would be able to extend their protection, potentially indefinitely, and this is contrary to the patent process.
Differentiating Canadian and U.S. Double Patenting Laws
In the United States, "same invention" or "co-terminus" double patenting is fatal in the U.S., but applicants can sidestep "obviousness-type" double patenting rejections through a terminal disclaimer. A terminal disclaimer results in the issuing patent expiring on the same date as the earliest filed patent. Unfortunately, Canadian patent law does not have an equivalent to the terminal disclaimer. Here, the patent doctrine seems to be in place to prevent patent owners from extending beyond the term afforded. Double patenting is always fatal in Canada.
Before the October 1989 amendments to the Canadian Patent Act, applicants could theoretically "evergreen" their patent term. They could file several patent applications covering the same subject matter, with slightly different claims. Today, the law calculates a patent’s term from the filing date regardless of the date of issuance, preventing evergreening.
Issues That Typically Arise in Double Patenting
Usually, risks of double patenting crop up in situations where one application cannot provide non-obvious elements or distinctions from the claims of a co-pending application. Here are some areas that come up frequently in discussions of double patenting.
Selection Patents
Selection patents involve filing a patent for a group of compounds from a larger class described in a prior patent. The prior or originating patent is usually based on the discovery of a new class of compounds. Like other applications, selection patents need to cover novel and non-obvious items. The compounds cannot have been previously disclosed - otherwise, the law cannot consider them to be novel. Also, if the compounds possess unique and unexpected properties, the invention may be considered non-obvious and eligible for a selection patent.
In Apotex Inc v Sanofi-Synthelabo Canada Inc, the Supreme Court of Canada provided a guide for decisions on novelty and non-obviousness for selection patents in the country. The suit involved whether selection patents are conceptually invalid and whether the selection patent in question was invalid on double patenting grounds. The Supreme Court ruled that selection patents are similar to other types of patents and are acceptable.
Continuation Practice
In the U.S., applicants can pursue additional claims disclosed in a previous or "parent" application. Canadian law does not include an equivalent to U.S. continuation practice. Canadian practice does permit voluntary divisional applications, as stated in Subsection 36(2) of the Canadian Patent Act. However, this situation can become problematic if the voluntary divisional application is broader than the parent patent.
Multiple Applications
Applications with different claim sets but substantially identical disclosures can also become a problem. Even if the claims of each application are for distinct inventive concepts, the dependent claims could combine various concepts and lead to double patenting issues.
Avoiding Double Patenting Problems
A proactive way to prevent double patenting problems in Canada is to consolidate related applications into a single application. Claim consolidation helps applicants avoid double patenting, especially in cases with multiple claim sets or substantially similar disclosures. Combining two claim sets into one can result in an Examiner requiring that the Applicant choose one set of claims and allows them to file the other claims in a divisional. When the Canadian Patent Office requires divisionals to be filed, a patent cannot be invalidated for double patenting.
Conclusions
Applicants who aren’t aware of the nuances of Canadian double patenting laws could find themselves in difficult situations regarding their patents. Understanding procedural mechanisms like the ones discussed above can help prevent double patenting issues.
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