Attacking divisional patents: is a new approach emerging?

For companies litigating patents in Canada (and beyond), we are seeing a growing trend of attacks on patents on the basis of double patenting—a second patent for the same or similar invention claimed in an earlier patent.

This trend is becoming more common particularly given the rise of divisional patents (often flowing from continuation-in-part applications in the United States).

Courts have traditionally held that once a divisional patent is issued by the patent office, it is beyond attack, and if an improper divisional application is approved, the ensuing divisional patent cannot be attacked—other than on the ground of double patenting¹. A 2020 Federal Court case, however, suggests that a new approach to attacking divisional patents may be emerging².

What is a divisional patent?

The Patent Act requires that “a patent shall be granted for one invention”³. If a patent application contains more than one invention, the surplus invention(s) can be “divided out” into a divisional application⁴, which can either be done voluntarily by the applicant, or may be required by the examiner⁵. A divisional application is given the same filing date as the original, or “parent” application⁶. A divisional application (which is deemed as its own distinct application) can further be divided into other divisional applications⁷. Because a divisional patent is deemed to have the same filing date as its parent application, it should not include any new subject matter outside of that which is already disclosed in the parent. (Of course, as we posit, if new matter is added, the reliance on the parent’s filing date is in jeopardy.)

But what happens where new matter is included in a divisional application, and that application is nevertheless allowed by the patent office?

The traditional approach

Traditional case law suggests that the new matter rule only applies to applications that are within the purview of the patent office—the patent office can object on this basis—but that once the application issues to patent, there is no recourse.

Where new matter has been added, double patenting should still apply, but there must be other avenues of recourse available.

This view was discussed in Merck & Co. Inc. v. Apotex Inc⁸. There, the defendant argued that a divisional patent was improperly granted because there was another application covering the same subject matter pending before the patent office⁹. Because the divisional application was improper, Apotex argued it was invalid, or at the very least, the divisional patent should have been given its actual filing date¹⁰. In obiter the Federal Court stated that the division of a patent is a procedural matter before the patent office and that once a patent issues a sufficient remedy can be found in double patenting¹¹. The Federal Court of Appeal concurred, reiterating that double patenting affords a sufficient remedy¹².

These cases, however, do not address the situation when new matter is added. When new matter is added, the divisional application should lose its claim to the filing date of its parent. It cannot be the case that divisional patents are shielded from scrutiny other than via the hyper-technical double patenting analysis. Where new matter has been added, double patenting should still apply, but there must be other avenues of recourse available, such as the filing date argument referenced above. The challenge will be to overcome the Federal Court of Appeal’s obiter comments that once a patent has issued, these arguments are spent.

A new approach

In light of the above, it came as a surprise to see the Federal Court, in Biogen Canada Inc. v. Taro Pharmaceuticals Inc., suggest that a new approach to attacking divisional patents may be available¹³. In this case, the plaintiff argued that their divisional application was “forced” (i.e., mandated by the patent office) and attempted to rely on the well-known rule that forced divisional patents are protected from attack¹⁴. This had been the argument traditionally used to readily and easily fend off double patenting allegations. Justice Manson found that the divisional application was voluntary—and not forced—because it was made in response to an objection, not a final action¹⁵. Further, the Court noted that reliance on Consolboard as “as a general proposition that patentees shall not be prejudiced by divisional applications is misguided¹⁶.”

Justice Manson’s view suggests that a patentee can be prejudiced by divisional applications and that divisional applications may well be open to attack¹⁷. It also suggests that the other ways to attack divisional patents—those other than double patenting—may be given airtime when they are argued in Court¹⁸. Lastly, it may limit the obiter found in Merck & Co. Inc. v. Apotex Inc.¹⁹: although that “improper divisional” argument was procedural, not all improper divisional arguments necessarily are.

What comes next?

The language in Biogen Canada Inc. v. Taro Pharmaceuticals Inc. creates a further crack in the longstanding approach to divisional patents. Filing multiple divisional applications is common practice²⁰, and a remedy should be available when they are filed improperly. In the years ahead, it will be interesting to see whether litigants use Justice Manson’s language to craft new attacks on divisional patents and how the courts respond to them.

What should companies filing patents keep in mind?

• Divide only when necessary: to keep your patents from being vulnerable to attack, ensure that a divisional application is the right approach from the outset to help mitigate double patenting litigation risk down the road.
• Apply scrutiny in the filing process: when filing a divisional application, be sure you are not adding new subject matter.
• Consider jurisdictional differences in process: for example, there are significant procedural distinctions between U.S. patent application (e.g., continuation-in-part and terminal disclaimer practices) and Canada, so strategies will need to be tailored accordingly.
• Consider any benefits of engaging the inventor in the process if litigation does arise, as in some cases it may help assert the intent and nature of the invention.

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¹ Merck & Co. Inc. v. Apotex Inc., 2006 FC 524 at paras. 201-204.

² Biogen Canada Inc. v. Taro Pharmaceuticals Inc., 2020 FC 621.

³ Patent Act, RSC, 1985 c. P-4, s. 36(1).

⁴ Patent Act, RSC, 1985 c. P-4, s. 36(2).

⁵ Patent Act, RSC, 1985 c. P-4, ss. 36(2), 36(2.1).

⁶ Patent Act, RSC, 1985 c. P-4, s. 36(4).

⁷ Patent Act, RSC, 1985 c. P-4, s. 36(4).

⁸ Merck & Co. Inc. v. Apotex Inc., 2006 FC 524.

⁹ Merck & Co. Inc. v. Apotex Inc., 2006 FC 524 at paras. 193-197.

¹⁰ Merck & Co. Inc. v. Apotex Inc., 2006 FC 524 at para. 201.

¹¹ Merck & Co. Inc. v. Apotex Inc., 2006 FC 524 at paras. 202-204.

¹² Merck & Co., Inc. v. Apotex Inc., 2006 FCA 323 at paras. 40, 49.

¹³ Biogen Canada Inc. v. Taro Pharmaceuticals Inc., 2020 FC 621.

¹⁴ Biogen Canada Inc. v. Taro Pharmaceuticals Inc., 2020 FC 621 at para. 197.

¹⁵ Biogen Canada Inc. v. Taro Pharmaceuticals Inc., 2020 FC 621 at para. 106.

¹⁶ Biogen Canada Inc. v. Taro Pharmaceuticals Inc., 2020 FC 621 at para. 199.

¹⁷ Biogen Canada Inc. v. Taro Pharmaceuticals Inc., 2020 FC 621 at paras. 197-199.

¹⁸ Biogen Canada Inc. v. Taro Pharmaceuticals Inc., 2020 FC 621 at para. 199.

¹⁹ Merck & Co. Inc. v. Apotex Inc., 2006 FC 524.

²⁰ See e.g. AstraZeneca Canada Inc. v. Canada (Minister of Health), 2006 SCC 49 at para. 39.