Invention Analysis and Claiming:
Markush Groups -- A Trap for the Unwary

By Ronald Slusky

The term ‘‘Markush group” refers to a list of alternatives set forth in a claim. In typical form, the Markush group is introduced by the phrase “selected from the group consisting of” as in the following claim that was at issue in the case that gave its name to this claiming construct— Ex parte Markush² :

1. The process for the manufacture of dyes which comprises coupling with a halogen- substituted pyrazolone, a diazotized unsulphonated material selected from the group consisting of aniline, homologues of aniline and halogen substitution products of aniline [emphasis added].

Markush claiming allows a number of species to be encompassed by a single independent claim in a situation where there is no generic term for the elements of the Markush group. Although deriving from chemical practice, Markush claiming is now used for all kinds of technologies.

Markush claiming can be very useful, but it can also be a trap for the unwary.

Consider, for example, the Markush group in claim 3 below.

2. A method for use in a processor-based device, the method comprising...

3. The method of claim 2 wherein said processor-based device is a selected one of a i) computer, ii) personal digital assistant and i...

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