Inre: Hitachi Metals, Ltd., 603 F. App'x 976

Background

Dispute concerns Hitachi patents: earlier U.S. Patent No. 4,792,368 (’368, filed 1983, issued 1988) and later U.S. Patent No. 5,645,651 (’651, filed 1995, issued 1997); ’651 extends well beyond the term of the ’368.
Both patents claim tetragonal crystalline magnetic compounds based on R(Fe,Co)B alloy systems; ’368 claims require elements from groups R and M; ’651 claims require additional elements from groups X and A and add Si to M.
Ex parte reexamination of the ’651 was requested; the examiner rejected several claims for obviousness-type double patenting over the ’368; the Board adopted that rejection as a new ground and sustained it; Hitachi appealed and requested rehearing (denied).
The Board relied on the ’368 specification showing common impurities and explicitly listing stability with small amounts of elements that overlap the ’651 A and X groups (e.g., C, P, Cu, F), interpreting “consisting essentially of” to permit such additives.
The Board concluded, and the court agreed, that the ’651 claims are obvious variants of the ’368 claims because the earlier claims, as properly construed, encompass compounds that include elements from the ’651 X and A groups as impurities.

Issues

Issue	Plaintiff's Argument	Defendant's Argument	Held
Whether claims of the ’651 patent are invalid for obviousness-type double patenting over the ’368 patent	Hitachi argued the ’651 claims are patentably distinct because they expressly require X and A elements (and Si) not claimed in the ’368	PTO/Board argued that the ’368 claims, properly construed with its specification and “consisting essentially of” language, encompass impurities/elements that fall within the ’651 X and A groups, making the later claims obvious variants	The court affirmed: the ’651 claims are not patentably distinct and are invalid for obviousness-type double patenting
Proper scope of earlier patent claims drafted as “consisting essentially of”	Hitachi contended the ’368 claims should be read narrowly to exclude the unclaimed X/A elements	Board/PTO relied on the ’368 specification showing stability with and presence of those elements as impurities, supporting inclusion under “consisting essentially of”	The court held that the specification supports including such additives; looking to the specification to define claim scope here was proper
Permissible use of specification in double patenting analysis	Hitachi argued reliance on the specification to read unclaimed elements into the claims improperly treats the specification as prior art	Board/PTO maintained that specification can be used to construe claim terms and identify embodiments for the double patenting test	The court agreed with the Board: the specification may be consulted to define claim terms and embodiments when assessing patentable distinctness
Whether inclusion of Si in ’651 M group affects distinctness	Hitachi argued differences in M (Si added) render claims distinct	The Board showed the sole substantial differences were elements from X and A; the slight M variance did not render claims distinct given other overlaps and impurities	Court affirmed that the minor M difference did not create patentable distinctness

Key Cases Cited

In re Gartside, 203 F.3d 1305 (Fed. Cir.) (§103 legal conclusion reviewed de novo; factual findings for substantial evidence)
Eli Lilly & Co. v. Barr Labs. Inc., 251 F.3d 955 (Fed. Cir.) (two-step obviousness-type double patenting framework)
In re Longi, 759 F.2d 887 (Fed. Cir.) (claims, not specification, are primary basis for double patenting; limited use of specification allowed to define claim terms)
Application of Vogel, 422 F.2d 438 (CCPA) (specification may be consulted to discern embodiments when assessing obvious variations)
Application of Herz, 537 F.2d 549 (CCPA) (construction of “consisting essentially of” may include additives supported by the specification)
Georgia-Pac. Corp. v. U.S. Gypsum Co., 195 F.3d 1322 (Fed. Cir.) (obviousness-type double patenting prevents term extension by obvious variants)