PCT AG-IP 5.118 What is permitted under the “Markush Practice”?

5.118.   What is permitted under the “Markush Practice”?  Rule 13.2 also governs the “Markush practice” wherein a single claim defines alternatives of an invention – a common drafting practice for inventions in the chemical field.  In this special situation, the requirement of a technical interrelationship and the same or corresponding special technical features as defined in Rule 13.2, is considered to be met when the alternatives are of a similar nature.

5.119.   When the Markush grouping is for alternatives of chemical compounds, they are regarded as being of a similar nature where the following criteria are fulfilled:

(i) all alternatives have a common property or activity, and

(ii) (a) a common structure is present – that is, a significant structural element is shared by all of the alternatives, or

  (b) 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.

5.120.   When dealing with alternatives, if it can be shown that at least one Markush alternative is not novel over the prior art, the question of unity of invention will be reconsidered by the examiner.  Reconsideration does not necessarily imply that an objection of lack of unity will be raised.

Source: http://www.wipo.int/pct/en/appguide/text.jsp?page=ip05.html

Date retrieved: 02 November 2015

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