Even an otherwise improper open Markush group may be interpreted as a definite closed group when the intrinsic record is reasonably clear in indicating what the claim intended to cover. Here, for example, a semiconductor substrate claimed as being “selected from the group comprising” different materials was found to be limited the recited group members—and the claims not indefinite—because the specification laid out a considerable list of exemplary substrates that corresponded to the specified materials. “Definiteness involves more than an examination of the technical correctness of the use of a Markush expression.” Although not the preferred drafting style, this case would be a good case to consult and cite in response to an indefiniteness rejection for an open Markush group when it may not be desirable to amend (e.g., during an IPR, a reexamination, etc.).
Background / Facts: The patent being asserted is directed to the fabrication of semiconductor devices using a substrate that has a textured surface in order to direct lattice defects to the sides and to reduce the defect density in the active layer. The base material of the substrate itself is relatively inconsequential to the invention, and is therefore claimed generically using a broad Markush group. Contrary to accepted Markush group practice, however, the claims recite that “said substrate is selected from the group comprising group III-V, group IV, group II-VI elements and alloys, ZnO, spinel and sapphire.”
Issue(s): Whether the claims are indefinite for their use of the phrase “said substrate is selected from the group comprising … .”
Holding(s): No. “We conclude that the district court erred in holding the claim indefinite in reciting an open Markush group. The issue before us on review from the district court is whether the claim is indefinite, not whether it recites an ‘improper’ Markush group. … 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. … The intrinsic record is reasonably definite in indicating what the claim covers because the specification lays out a considerable list of exemplary substrates that correspond to the materials specified in the claim and combinations thereof. … We therefore conclude that the reasonably ascertainable meaning of the contested claim language is that the substrate must contain one or more of the enumerated members of the claimed group.”