The U.S. Patent and Trademark Office (“USPTO”) quietly increased the examiners’ arsenal by slipping a new rejection into the latest revision of the Manual of Patent Examining Procedure (“MPEP”) released last month. One of the changes made in this revision is the addition of a new “improper Markush grouping” section, MPEP § 706.03(y), which authorizes patent examiners to reject a claim on the basis that it contains an improper listing of alternative elements. Patent applications in the life sciences, which frequently have claims in the “Markush” format, may soon face the new “improper Markush grouping” rejections.

A “Markush” claim format is often used as a straightforward way to capture various alternatives for a given element in a single claim. It is named after the patent applicant (Eugene A. Markush) who used this format in a court case that was decided in 1924. Markush claims contain a customized list of elements that are useful for the purposes of the claim. As an example, for the purposes of describing various alternative materials to coat an implant screw, a claim could contain a list such as “ceramic, glass, plastic, or metal.”

Prior to the recent MPEP revision, improper Markush grouping rejections had been uncommon because they were based on guidelines issued by the USPTO in 2011. However, now that the new section has been added to the MPEP, it is expected that rejections of patent applications based on improper Markush grouping will become much more frequent. The examiner can now make a rejection based on improper Markush grouping if the examiner determines that the members of a Markush group lack either a single structural similarity or a common use, or if the single structural similarity is a substantial structural feature of a chemical compound that is not essential to the common use. As to timing, the examiner should make a rejection based on an improper Markush grouping in the first action on the merits after presentation of the claim with the allegedly improper Markush grouping.

When making the improper Markush grouping rejection, the new MPEP section instructs the examiner to include suggestions for the applicant as to how to overcome the rejection, e.g., by suggesting a proper Markush grouping based on the specification as filed and/or by suggesting that applicant set forth each alternative (or grouping of patentably indistinct alternatives) within an allegedly improper Markush grouping in a series of independent or dependent claims. In doing so, the examiner cannot suggest any grouping that clearly would not meet the requirements of 35 U.S.C. § 112(a). For example, the examiner should not suggest a grouping that meets the requirements for a proper Markush grouping, but which would clearly lack adequate written description if presented in a separate claim.

The new MPEP section states that an improper Markush grouping rejection can be overcome by (1) amending the rejected claim such that the Markush grouping includes only members that share a single structural similarity and a common use; or (2) by presenting convincing arguments why the members of the Markush grouping share a single structural similarity and common use (i.e., are members of a physical, chemical, or art-recognized class that share a common use, or are chemical compounds that share a substantial structural feature that is essential to the common use).

In addition, even if the applicant does not take action sufficient to overcome the improper Markush grouping rejection, when all of the claims are otherwise in condition for allowance the examiner is instructed to reconsider the propriety of the improper Markush grouping rejection. If the examiner determines that in light of the prior art and the record as a whole the alternatives of the Markush grouping share a single structural similarity and a common use, then the rejection should be withdrawn. Note that no Markush claim can be allowed until any improper Markush grouping rejection has been overcome or withdrawn, and all other conditions of patentability have been satisfied.

The USPTO, by introducing section 706.03(y) into the MPEP, has taken the position that improper Markush grouping is a rejection on the merits and can be appealed to the PTAB. When drafting a Markush claim, patent practitioners should keep this new MPEP section in mind and recite members of the Markush grouping that share a single structural similarity and common use.