How does the USPTO handle antecedent basis issues in Markush groups?
The USPTO has specific guidelines for handling antecedent basis issues in Markush groups, which are alternative limitations in patent claims. According to MPEP 2173.05(e):
“A Markush group that lists alternative members does not provide antecedent basis for a later claim to one of the members as a individual element. For example, if a claim recites a member selected from the group consisting of A, B, and C, a later limitation to A, B or C, or any of the individual members would lack antecedent basis.”
This means that if you use a Markush group to list alternatives, you can’t later refer to one of those alternatives individually without reintroducing it. For example:
- Correct: “A composition comprising a member selected from the group consisting of A, B, and C, wherein the member is present in an amount of…”
- Incorrect: “A composition comprising a member selected from the group consisting of A, B, and C, wherein A is present in an amount of…” (lacks antecedent basis for A as an individual element)
To avoid antecedent basis issues with Markush groups, either reintroduce the specific element or refer to it as “the member” rather than by its individual name.
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