Imagine That IP Law Blog

In patent claim drafting, two distinct ways to claim combinations of elements are Markush and Superguide constructions. Both approaches have been explored in recent case law, particularly with respect to the significance of proper syntax when reciting the limitation of “at least one” when it precedes a series of elements. A closer look at both the Markush and Superguide approaches for reciting elements in combination offers guidance to avoid traps for the unwary.

Superguide
Of the two, the Superguide construction is likely simpler. In exploring Superguide v. DirecTV as a basis for patent validity, we previously noted that this approach involves a simple test: does your claim recite “OR” or does your claim recite “AND” when listing a series of elements?  SuperGuide Corp. v. DirecTV Enters., Inc., 358 F.3d 870 (Fed. Cir. 2004). In SuperGuide, the Federal Circuit noted how “at least one of A, B, or C” is interpreted differently than “at least one of A, B, and C.”  Specifically, if the Applicant intends to claim combinations of the elements, the proper language is “at least one of A, B or C.” Otherwise, if the claims recite “and” instead of “or”, SuperGuide dictates that the plain meaning of “at least one of A, B, and C” means: at least one A, at least one of B and at least one of C.

While a Superguide construction that includes the language, “at least one of A, B, or C”, for reciting elements in combination provides a straightforward approach, Markush claims have more layers of complexity.

Markush
As generally defined by MPEP 2173.05(h), a Markush claim is “claim which recites a list of alternatives to define a limitation....” For example, a hypothetical Markush claim may recite:

            “an X selected from the group consisting of A, B, and C”

The first issue when using a Markush claim, then, is how to recite the elements in combination.

In answering this question, the Federal Circuit has noted that “if a Markush claim recites “a member selected from the group consisting of A, B, and C,” the claim is presumed to permit the member to be one and only one of A, B, or C, and to exclude mixtures or combinations of A, B, and C.” (Multilayer Stretch Cling Film Holdings, Inc. v. Berry Plastics Corp., 831 F.3d 1350, 1363 (Fed. Cir. 2016)). However, “[i]f a claim is intended to encompass combinations or mixtures of the alternatives set forth in the Markush grouping, the claim may include qualifying language preceding the recited alternatives (such as "at least one member" selected from the group), or within the list of alternatives (such as "or mixtures thereof").” MPEP 2173.05(h) (e9 r07. 2022) (citing Abbott Labs v. Baxter Pharmaceutical Products, Inc., 334 F.3d 1274, 1281 (Fed. Cir. 2003)).

So referring again to the hypothetical Markush claim above, to modify this claim so that it would recite a combination of elements, the following may be recited:

            “at least one X selected from the group consisting of A, B, and C”

And to recite a mixture as opposed to a combination, the following may be considered:

            “an X selected from the group consisting of A, B, and C, or mixtures thereof”

The second issue when using a Markush claim to recite elements in combination concerns using proper syntax, so that Examiners at the Patent Office will recognize the language as a Markush claim and not reject it as indefinite under 35 U.S.C. § 112(b). With regard to the proper syntax of a Markush group, the MPEP states that “[a] Markush grouping is a closed group of alternatives, i.e., the selection is made from a group “consisting of” (rather than “comprising” or “including”) the alternative members.” MPEP 2173.05(h) (e9 r07. 2022). Further, as explained by the Federal Circuit:

“A Markush group by its nature is closed. If an applicant tries to claim a Markush group without the word “consisting,” the PTO will insist upon the addition of this word to ensure a closed meaning. Thus, in order to “close” a Markush group, the PTO insists on the transition phrase “group consisting of.” See Abbott Labs. V. Baxter Pharm. Prods., Inc., 334 F.3d 1274, 1280 (Fed. Cir. 2003). Without the word “consisting” the simple phrase “group of” is presumptively open.”
Gillette Co. v. Energizer Holdings, Inc., 405 F.3d 1367, 1372 (Fed. Cir. 2005)

Accordingly, a Markush group is a closed group, meaning that it requires the transitional phrase “consisting of”.  So a properly formed Markush claim that recites a combination of elements, may state:

            “at least one X selected from the group consisting of A, B, and C”

Reciting the aforementioned claim language without including the transitional phrase “consisting of” raises the risk that if the Patent Office fails to spot the missing “consisting of” language in the Markush claim, the issue of § 112(b) indefiniteness may subsequently be reviewed by the courts. Whether a claim is indefinite under 35 USC § 112(b) simply for improperly reciting Markush group syntax will depend on a court’s interpretation of the claims in light of the specification. Specifically, the Federal Circuit observes that:

“It is the job of the Patent and Trademark Office to ensure, on examination, that a claim is definite and that, when a Markush expression is used, it is used properly. But that is not our task in reviewing a claim that has been held to be indefinite. Our task involves determining the definiteness of a claim, i.e., whether the district court erred in finding the claim to be indefinite, not evaluating the propriety of Markush language.

Definiteness involves more than an examination of the technical correctness of the use of a Markush expression that may have slipped past the examining process. It involves evaluation of the claim in light of the written description.”
Lexington Luminance LLC v. Amazon.com Inc., 601 F. App’x 963, 968 (Fed. Cir. 2015)

Conclusion
Therefore, to recite elements in combination, the entire issue and complexity of a Markush group can be avoided by merely using the Superguide syntax (e.g., “at least one of A, B, or C”). Alternatively, when using a Markush group, practitioners are advised to use the proper closed form syntax of “at least one X selected from a group consisting of A, B, and C.” This avoids a potential issue where a Court will have to address the effect of the improperly formed Markush syntax slipping by the Patent Office.