Does Double Patenting Need New Rules?

• Author: Alan Macek
• Date: November 09, 2015

Patents have been described as a quid pro quo – in return for disclosure of the invention, the inventor gets a time limited exclusive period to practice the invention. There are a number of rules and restrictions that restrict the ability to extend patent rights – i.e. get more than the patent owner bargained for, including ‘double patenting’ but some of the earlier concerns about extending patent protection through double patenting no longer apply under our current Patent Act which requires that patents and any divisional patents expire on the same day.

Double patenting is a restriction on getting multiple patents for the same or similar invention. This has been described by the Supreme Court of Canada in Whirlpool Corp v. Camco Inc., 2000 SCC 67 as follows:

The prohibition against double patenting relates … to the “evergreen” problem … The inventor is only entitled to “a” patent for each invention: Patent Act, s. 36(1). If a subsequent patent issues with identical claims, there is an improper extension of the monopoly.

The Supreme Court has described two types of double patenting: “same invention” and “obviousness”. The first type applies where there are two patents for the same invention. The second, which arises more frequently, applies where a second patent is not ‘patentably distinct’ from the first patent by being obvious or lacking novelty in view of the first patent. This may arise when the second patent is an improvement or refinement of the first patent.

Much of the case law on double patenting arises from ‘Old Act’ patents, patents filed prior to 1989 when the term of protection was 17 years from the date the patent was granted. In contrast, patent applications filed after 1989, known as ‘New Act’ patents, last 20 years from the filing date.

This distinction is important particularly for divisional applications – applications which are filed after an original parent application but are so closely related they claim priority back to a parent application such that the divisional application is deemed to have the same filing date as the original application. The Section 36 of the Patent Act governs divisional applications:

36(4) A divisional application shall be deemed to be a separate and distinct application under this Act, to which its provisions apply as fully as may be, and separate fees shall be paid on the divisional application and it shall have the same filing date as the original application.

Under the ‘Old Act’, divisional...