Understanding The Reach And Limits Of Markush Claims

The term Markush owes its existence to Eugene A. Markush, who was the applicant in US patent *720. He used it in a claim, a type of definition of a genus or subgenus by enumeration of species. In fact, this practice was in use before the rejection of such types of claims in the Markush application. The reason for the rejection of this type of claim in this case was that the examiner considered this claim to be a mere alternative in form. On petition before the commissioner (Ex parte Markush, 1925 CD 126 (Com. Pat. 1924), the form of claim was approved, and the petition was allowed, thus requiring the examiner to examine it for patentability. Thus, the name "Markush" became attached to a type of claim expression, and that is all it connotes. However, further decisions and opinions on similar petitions and appeals ensued after the Markush ruling, and a considerable body of case law evolved, approving and disapproving various forms of Markush-type expression, from which