There are generally two types of double patenting rejections. One is the “same invention” type double patenting rejection based on 35 U.S.C. 101 which states in the singular that an inventor “may obtain a patent.” The second is the “nonstatutory-type” double patenting rejection based on a judicially created doctrine grounded in public policy and which is primarily intended to prevent prolongation of the patent term by prohibiting claims in a second patent not patentably distinct from claims in a first patent.
The doctrine of nonstatutory double patenting also seeks to prevent the possibility of multiple suits against an accused infringer by different assignees of patents claiming patentably indistinct variations of the same invention. In re Van Ornum, 686 F.2d 937, 944-48, 214 USPQ 761, 767-70 (CCPA 1982). The submission of a terminal disclaimer in compliance with 37 CFR 1.321(b) to overcome a double patenting rejection ensures that a patent owner with multiple patents claiming obvious variations of one invention retains all those patents or sells them as a group. Van Ornum, 686 F.2d at 944-45, 214 USPQ at 767.
Nonstatutory double patenting includes rejections based on anticipation, a one-way determination of “obviousness,” or a two-way determination of “obviousness.” It is important to note that the “obviousness” analysis for “obviousness-type” double-patenting is “similar to, but not necessarily the same as, that undertaken under 35 U.S.C. 103.” In re Braat, 937 F.2d 589, 592-93, 19 USPQ2d 1289, 1292 (Fed. Cir. 1991) (citing In re Longi, 759 F.2d 887, 892 n.4, 225 USPQ 645, 648 n.4 (Fed. Cir. 1985)); Geneva Pharmaceuticals, 349 F.3d 1373, 1378 n.1, 68 USPQ2d 1865, 1869 n.1 (Fed. Cir. 2003). In addition, nonstatutory double patenting also includes rejections based on the equitable principle against permitting an unjustified timewise extension of patent rights. See In re Schneller, 397 F.2d 350, 158 USPQ 210 (CCPA 1968)