By Matthew Rizzolo (May 2, 2018, 12:30 PM EDT) -- In the recent case of Oil States v. Greene's, the U.S. Supreme Court upheld the constitutionality of inter partes review — the popular proceedings created in the America Invents Act and commonly used by defendants to challenge the validity of patents. In doing so, however, the Supreme Court reaffirmed that patents are property rights that are protected by the due process and takings clauses of the Fifth Amendment.[1] In the wake of Oil States, some have wondered whether patent owners might raise other constitutional challenges to inter partes review or other U.S. Patent and Trademark Office post-grant proceedings, and much of the initial attention has focused on the due process clause. But the court's reference to the takings clause has received less scrutiny. Clues to what might happen next may come from a surprising place in history — legislation and litigation involving conversions of abandoned railroads to bike trails....