2173.05(h) Alternative Limitations [R-10.2019]
I. MARKUSH GROUPS
A claim which recites a list of alternatives to define a limitation is an acceptable claim construction which should not necessarily be rejected as confusing under 35 U.S.C. 112(b) or as improper. See MPEP § 2117 for guidelines regarding the determination of whether a Markush grouping is improper.
Treatment of claims reciting alternatives is not governed by the particular format used (e.g., alternatives may be set forth as "a material selected from the group consisting of A, B, and C" or "wherein the material is A, B, or C"). See, e.g., the Supplementary Examination Guidelines for Determining Compliance with 35 U.S.C. 112 and for Treatment of Related Issues in Patent Applications ("Supplementary Guidelines"), 76 Fed. Reg. 7162, 7166 (February 9, 2011). Claims that set forth a list of alternatives from which a selection is to be made are typically referred to as Markush claims, after the appellant in Ex parte Markush, 1925 Dec. Comm’r Pat. 126, 127 (1924). The listing of specified alternatives within a Markush claim is referred to as a Markush group or Markush grouping. Abbott Labs v. Baxter Pharmaceutical Products, Inc., 334 F.3d 1274, 1280-81, 67 USPQ2d 1191, 1196-97 (Fed. Cir. 2003) (citing to several sources that describe Markush groups).
See MPEP § 2117 for a general discussion of Markush claims and guidelines regarding the determination of whether a Markush grouping is improper, and MPEP § 803.02 for a discussion of election requirements in Markush claims.
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. Abbott Labs., 334 F.3d at 1280, 67 USPQ2d at 1196. If a Markush grouping requires a material selected from an open list of alternatives (e.g., selected from the group "comprising" or "consisting essentially of" the recited alternatives), the claim should generally be rejected under 35 U.S.C. 112(b) as indefinite because it is unclear what other alternatives are intended to be encompassed by the claim. If 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"). Id. at 1281. See also MPEP § 2111.03.
A Markush grouping may include a large number of alternatives, and as a result a Markush claim may encompass a large number of alternative members or embodiments, but a claim is not necessarily indefinite under 35 U.S.C. 112(b) for such breadth. In re Gardner, 427 F.2d 786, 788, 166 USPQ 138, 140 (CCPA 1970) ("Breadth is not indefiniteness."). In certain circumstances, however, a Markush group may be so expansive that persons skilled in the art cannot determine the metes and bounds of the claimed invention. For example, if a claim defines a chemical compound using one or more Markush groups, and that claim encompasses a massive number of distinct alternative members, the claim may be indefinite under 35 U.S.C. 112(b) if one skilled in the art cannot determine its metes and bounds due to an inability to envision all of the compounds defined by the Markush group(s). In such a circumstance, a rejection of the claim for indefiniteness under 35 U.S.C. 112(b) is appropriate.
The use of Markush claims of diminishing scope should not, in itself, be considered a sufficient basis for objection to or rejection of claims. However, if such a practice renders the claims indefinite or if it results in undue multiplicity, an appropriate rejection should be made.
Similarly, the double inclusion of an element by members of a Markush group is not, in itself, sufficient basis for objection to or rejection of claims. Rather, the facts in each case must be evaluated to determine whether or not the multiple inclusion of one or more elements in a claim renders that claim indefinite. The mere fact that a compound may be embraced by more than one member of a Markush group recited in the claim does not necessarily render the scope of the claim unclear. For example, the Markush group, "selected from the group consisting of amino, halogen, nitro, chloro and alkyl" should be acceptable even though "halogen" is generic to "chloro." See, e.g., Eli Lilly & Co. v. Teva Parenteral Meds., 845 F.3d 1357, 1371,121 USPQ2d 1277, 1287 (Fed. Cir. 2017) (redundancy of including both "vitamin B12" and "cyanocobalamin" (which were recognized on the record as referencing the same compound) within a Markush group of methylmalonic acid lowering agents did not render the claims indefinite).
Another alternative format which requires some analysis before concluding whether or not the language is indefinite involves the use of the term "optionally." In Ex parte Cordova, 10 USPQ2d 1949 (Bd. Pat. App. & Inter. 1989) the language "containing A, B, and optionally C" was considered acceptable alternative language because there was no ambiguity as to which alternatives are covered by the claim. A similar holding was reached with regard to the term "optionally" in Ex parte Wu, 10 USPQ2d 2031 (Bd. Pat. App. & Inter. 1989). In the instance where the list of potential alternatives can vary and ambiguity arises, then it is proper to make a rejection under 35 U.S.C. 112(b) and explain why there is confusion.