By Joseph Mallon (February 6, 2018, 3:33 PM EST) -- Patent litigators are closely studying a new "improper Markush grouping" section that was quietly slipped into the latest revision of the Manual of Patent Examining Procedure released by the U.S. Patent and Trademark Office last month, just days prior to the Senate confirmation of Andrei Iancu as the new director. The MPEP functions as an instruction manual for patent examiners, providing the current procedures examiners are required or authorized to follow in the examination of patent applications. Although the MPEP does not have the force of law, it reflects current USPTO policy and thus is highly influential, as evidenced by numerous citations by federal courts to the MPEP in their assessments of patent validity....