Takeda Pharmaceutical Co., Ltd. v. Doll, 2008-1131, April 10, 2009 (link)
Takeda originally filed a patent application disclosing certain cephem compounds and the process for making those compounds in Japan in 1974, and in the U.S. in 1975. Since that time, Takeda filed a series of continuation applications (filed under the "old", pre-June 1995 regime) in the PTO, many of which issued as patents.
In 1998, the PTO received 2 anonymous requests for reexamination, asserting that one of the patents was invalid for "obviousness-type" double patenting in view of Takeda's prior patents and other prior art. During the PTO proceedings, Takeda put forth evidence that the later-filed method was a materially distinct process. However, the PTO held that, since the evidence was developed after the date of the original invention (i.e., 1974-75), it could not be used to defeat the double-patenting rejection.
Takeda appealed to the district court, and the court overturned the double patenting rejection, concluding that "subsequent developments in the art [are relevant to] determining whether alternative processes exist" when weighing patentable distinctions for double patenting.
On appeal, the CAFC ponders the problem thus:
The novel legal question in this case asks if later-developed alternative processes are relevant in the product-process "patentably distinct" inquiry. The PTO contends that the date of invention, in this case December 19, 1974, governs the relevance of products and processes in the double patenting context. Thus, the PTO submits that the date of invention governs the timing of double patenting analyses because other issues relating to patentability are judged from the date of invention . . . In the alternative, the PTO posits that alternative processes must at least appear before issuance of the primary patent application.
Takeda, on the other hand, argues that the PTO’s approach is too limited. In its view, processes developed after the date of invention deserve a role in the double patenting calculus.
After considering each argument, the CAFC chose its own approach, ruling that future developments leading up to the secondary application (which actually triggers the potential of double patenting) may be considered:
The secondary application (in this case, the process application of January 8, 1990) actually triggers the potential of an "unjustified extension of patent term." When filing the secondary application, the applicant essentially avers that the product and process are "patentably distinct." Thus, the relevant time frame for determining whether a product and process are "patentably distinct" should be at the filing date of the secondary application. In this case, Takeda filed the ’216 process patent application on January 8, 1990. This approach allows an applicant to rely on some later-developed methods to show that the product and process are "patentably distinct," even though the alternative processes for making that product may not have been known at the filing date of the primary application. This rule gives the applicant the benefit of future developments in the art. At the same time, however, it prevents the inequitable situation that arises when an applicant attempts to rely on developments occurring decades after the filing date of the secondary application.
[W]hile the majority’s approach is more restrictive than that urged by Takeda, it still allows Takeda to exclude sixteen years of prior art for invalidity purposes (such as 35 U.S.C. §§ 102, 103), while simultaneously taking advantage of that art to overcome a double-patenting rejection. This is what troubles me about the majority’s understandable desire to find a middle ground in this case. It allows Takeda to have it both ways. In addition, as far as I can tell, there is no other doctrine or rule that allows unpatentable material to spring back into patentability based on later developments in the field.