A patent law doctrine that prevents a patentee from securing two patents on the same invention.

Further Reading:

Perricone, M.D. v. Medicis Pharm. Corp., 432 F.3d 1368 (Fed. Cir. 2005):

The double patenting doctrine generally prevents a patentee from receiving two patents for the same invention. Thus, this doctrine polices the proper application of the patent term for each invention. The proscription against double patenting takes two forms: statutory and non-statutory. Statutory, or “same invention,” double patenting is based on the language in § 101 of the Patent Act mandating “a patent” for any new and useful invention. 35 U.S.C. § 101 (2000); In re Goodman, 11 F.3d 1046, 1052 (Fed.Cir.1993) (“If the claimed inventions are identical in scope, the proper rejection is under 35 U.S.C. § 101 because an inventor is entitled to a single patent for an invention.”) (citations omitted). Non-statutory, or “obviousness-type,” double patenting is a judicially created doctrine adopted to prevent claims in separate applications or patents that do not recite the “same” invention, but nonetheless claim inventions so alike that granting both exclusive rights would effectively extend the life of patent protection.

Symbol Tech., Inc. v. Opticon, Inc., 935 F.2d 1569 (Fed. Cir. 1991):

Double patenting is an affirmative defense. Studiengesellschaft Kohle v. Northern Petrochemical Co., 784 F.2d at 352, 228 USPQ at 838. Opticon was therefore required to prove double patenting by clear and convincing evidence, a heavy and unshifting burden. RCA Corp. v. Applied Digital Data Sys., Inc., 730 F.2d 1440, 1444, 221 USPQ 385, 387 (Fed.Cir.1984) (invalidity requires clear and convincing proof, and burden remains at all times with patent challenger); Carman Indus., Inc. v. Wahl,724 F.2d 932, 940, 220 USPQ 481, 487 (Fed.Cir.1983) (“[t]here is a heavy burden of proof on one seeking to show double patenting”).