In 2005 the U.S. Court of Appeals for the Federal Circuit first articulated the blocking-patent doctrine in Merck & Co. v. Teva Pharmaceuticals USA Inc., 395 F.3d 1364 (Fed. Cir. 2005), or Merck I. The Federal Circuit said that under the doctrine courts may reduce the weight given to evidence of commercial success where an earlier patent blocked market entry by others. The appellate court later explained in Acorda Therapeutics Inc. v. Roxane Laboratories Inc., 903 F.3d 1310 (Fed. Cir. 2018), that a patent is a blocking patent "where the practice of a later invention would infringe the earlier patent." The rationale behind the doctrine was that where others are legally barred from commercializing a purportedly obvious idea due to a preexisting patent, the court may conclude that the inference of nonobviousness from evidence of commercial success is weak.