¶ 18.07.03    Heading – Chemical Compound Alternatives of Markush Group Are Not of a Similar Nature

Where a single claim defines alternatives of a Markush group, the requirement of a technical interrelationship and the same or corresponding special technical features as defined in Rule 13.2, is considered met when the alternatives are of a similar nature. When the Markush grouping is for alternatives of chemical compounds, the alternatives are regarded as being of a similar nature where the following criteria are fulfilled:

    • (A) all alternatives have a common property or activity; AND
    • (B)
      • (1) a common structure is present, that is, a significant structural element is shared by all of the alternatives; OR
    • (B)
      • (2) in cases where the common structure cannot be the unifying criteria, all alternatives belong to a recognized class of chemical compounds in the art to which the invention pertains.

The phrase "significant structural element is shared by all of the alternatives" refers to cases where the compounds share a common chemical structure which occupies a large portion of their structures, or in case the compounds have in common only a small portion of their structures, the commonly shared structure constitutes a structurally distinctive portion in view of existing prior art, and the common structure is essential to the common property or activity.

The phrase "recognized class of chemical compounds" means that there is an expectation from the knowledge in the art that members of the class will behave in the same way in the context of the claimed invention, i.e. each member could be substituted one for the other, with the expectation that the same intended result would be achieved.

Examiner Note:

1. This heading should be used when the chemical alternatives of a Markush group are determined to lack unity of invention.

2. Follow with form paragraphs listed using form paragraphs 18.07.03a - 18.07.03c, as appropriate.