SAN FRANCISCO — A Chicago patent attorney and his client are trying to shut down inter partes review, arguing that the procedure that has reshaped U.S. patent litigation is unconstitutional.

Robert Greenspoon of Flachsbart & Greenspoon is asking the U.S. Court of Appeals for the Fourth Circuit to rule that once the U.S. Patent and Trademark Office issues a valid patent, only an Article III court—and not an administrative court like the Patent Trial and Appeal Board—can take it away.