Patent Bar Practice Exam 2025 - Free Patent Bar Practice Questions and Study Guide

A Markush group is a term used in patent law to describe a specific type of claim that allows an applicant to define a broad category of compounds or materials by listing representative members of that group. This method of claiming provides flexibility, enabling inventors to claim various alternatives without the necessity of describing each possible variant in detail.

The correct expression is that R is selected from the group consisting of A, B, C, and D. This phrasing emphasizes that R can be one of the specific items mentioned without implying that the group may include additional, unlisted items. The use of “consisting of” indicates an exclusive list, which is crucial in patent claims to ensure that the combinations defined do not extend beyond what is specifically recited. This precise wording helps delineate the scope of the claim, making it clear that only the specified members are included.

In contrast, using “comprising” introduces the possibility of including additional, unspecified members, which can extend the scope of the claim beyond the defined members. This might not be appropriate when a precise definition is needed.

The use of “or” in one of the options suggests an alternative between members rather than indicating that R can be one of the listed members, which does not capture the essence of