A district court's determination of validity under 35 U.S.C. § 251 is a question of law that we review de novo. Forum US, Inc. v. Flow Valve, LLC, 926 F.3d 1346, 135051 (Fed. Cir. 2019).
The Board's assessment of whether new claims presented in a reissue application comply with 35 U.S.C. § 251 is a question of law that we review de novo, based on underlying findings of fact reviewed for substantial evidence. Forum US, Inc. v. Flow Valve, LLC, 926 F.3d 1346, 1350-51 (Fed. Cir. 2019). B. Analysis
Antares, 771 F.3d at 1362. That is, the original specification “must do more than merely suggest or indicate the invention recited in reissue claims.” Forum US, Inc. v. Flow Valve LLC, 926 F.3d 1346, 1351 (Fed. Cir. 2019); see also U.S. Indus. Chems., Inc. v. Carbide & Carbon Chems. Corp., 315 U.S. 668, 676 (1942).
To satisfy the original patent requirement, "the original patent 'must clearly and unequivocally disclose the newly claimed invention [in the reissued patent] as a separate invention.' " Forum US, Inc. v. Flow Valve, LLC, 926 F.3d 1346, 1352 (Fed. Cir. 2019) (quoting Antares Pharma, Inc. v. Medac Pharma Inc., 771 F.3d 1354 (Fed. Cir. 2014)). "Whether new claims in a reissue patent comply with 35 U.S.C. § 251 is a question of law[.]" Id. at 1350-51.
Compliance with the original patent requirement is a question of law. Forum US, Inc. v. Flow Valve, LLC , 926 F.3d 1346, 1350–51 (Fed. Cir. 2019).
However, “for broadening reissue claims, the specification of the original patent must do more than merely suggest or indicate the invention recited in reissue claims; ‘[i]t must appear from the face of the instrument that what is covered by the reissue was intended to have been covered and secured by the original.” Forum US, Inc. v. Flow Valve, LLC, 926 F.3d 1346, at 1351-52 (Fed. Cir. 2019) (quoting U.S. Indus. Chems., 315 U.S. at 676) (emphasis in original). Thus, “the essential inquiry under the ‘original patent' clause of § 251 . . . is whether one skilled in the art, reading the specification, would identify the subject matter of the new claims as invented and disclosed by the patentees.”
. But reissued patents must be for the same invention as set out in the original patent, Antares Pharma, Inc. v. Medac Pharma Inc., 771 F.3d 1354, 1359-60 (Fed. Cir. 2014) (quoting 35 U.S.C. § 64 (1946); Forum US, Inc. v. Flow Valve, Ltd. Liab. Co., 926 F.3d 1346, 1351 (Fed. Cir. 2019); U.S. Indus. Chems., Inc. v. Carbide & Carbon Chems. Corp., 315 U.S. 668, 676 (1942) (interpreting 35 U.S.C. § 64 (1934)) (“[I]t is not enough that an invention might have been claimed in the original patent because it was suggested or indicated in the specification.”); accord Corbin Cabinet Lock Co. v. Eagle Lock Co., 150 U.S. 38, 42-43 (1893)
See also Forum US, Inc. v. Flow Valve, LLC, 926 F.3d 1346, 1351 (Fed. Cir. 2019) (“The legal conclusion regarding § 251 compliance, however, can involve underlying questions of fact....[T]he court may consider expert evidence to ascertain the meaning of a technical or scientific term or term of art so that the court may be aided in understanding not what the instruments mean but what they actually say.” (cleaned up)).