On March 27, 2014, the U.S. Court of Appeals for the Federal Circuit declined to reconsider its previous decision that shifted the burden of proof in certain patent infringement cases from the alleged infringer to the patentee. The order denying the petition for reconsideration was a setback for WLF, which filed a brief arguing that the party challenging patent validity should always bear the burden of demonstrating invalidity. The panel held that in cases (as here) in which the alleged infringer demonstrates that “prior art” may have disclosed the product that was later patented, the burden falls on the patent holder to come forward with evidence demonstrating that the patent should nevertheless not be deemed to have been anticipated. The panel held that the patent holder had failed to make the required demonstration. In urging the court to grant rehearing en banc, WLF argued that shifting the burden is inconsistent with the presumption that a patent issued by the PTO is valid.