Mealey's (May 7, 2018, 11:36 AM EDT) -- WASHINGTON, D.C. — In a May 4 holding, the Federal Circuit U.S. Court of Appeals affirmed findings by a North Dakota federal judge that a hydraulic fracturing patent is unenforceable due to an inventor’s inequitable conduct before the U.S. Patent and Trademark Office (PTO) (Energy Heating LLC, et al. v. Heat-On-The-Fly LLC, et al., Nos. 2016-1559, -1893, -1894, Fed. Cir.)....