While the patent statute does not provide for product-by-process claims, the courts have long recognized the appropriateness of such claims. See, e.g., In re Thorpe, 777 F.2d 695, 697 (Fed. Cir. 1985); In re Brown, 59 C.C.P.A. 1036, 459 F.2d 531, 535 (1972); In re Steppan, 55 C.C.P.A. 791, 394 F.2d 1013, 1018 (1967). The purpose of product-by-process claims is to allow inventors to claim "an otherwise patentable product that resists definition by other than the process by which it is made."

Scripps correctly points out that this statement appears to diverge from our precedent, recognizing that this precedent arose in the context of patent prosecution, not patent infringement. E.g., In re Thorpe, 777 F.2d 695, 227 USPQ 964 (Fed. Cir. 1985) (holding that prior art pertinent only to product is proper ground for rejecting product-by-process claims); In re Brown, 459 F.2d 531, 535, 173 USPQ 685, 688 (CCPA 1972) (in product-by-process claims the patentability of the product must be established independent of the process); In re Bridgeford, 357 F.2d 679, 682 n. 5, 149 USPQ 55, 58 n. 5 (CCPA 1966) (recognizing that some courts in infringement litigation have construed product-by-process claims as limited to the particular process, but holding that patentability is determined independent of the process). In determining patentability we construe the product as not limited by the process stated in the claims.

The Federal Circuit then stated that the claim limitations that follow should define the "process by which [the structure claimed] is made." Id. (citing In re Thorpe, 777 F.2d 695, 697 (Fed. Cir. 1985)). The current claims present very different issues than the issues raised in Downing.

Such "product-by-process" claims "enable an applicant to claim an otherwise patentable product that resists definition by other than the process by which it is made." In re Thorpe, 777 F.2d 695, 697 (Fed. Cir. 1985). And though defined by its manufacturing process, "the invention so defined is a product and not a process."

In Scripps Clinic Research Found. v. Grenentech, the Federal Circuit held that "[s]ince claims must be construed the same way for validity and for infringement, the correct reading of product-by-process claims is that they are not limited to product prepared by the process set forth in the claims." 927 F.2d 1565, 1583 (Fed. Cir. 1991) (citing In re Thorpe, 777 F.2d 695 (Fed. Cir. 1985)). The following year, a different panel of the Federal Circuit decided Atlantic Thermoplastics Co., Inc. v. Faytex Corp., 970 F.2d 834 (Fed. Cir. 1992), reh'g en banc denied, 974 F.2d 1299.

In that case the product-by-process claim is not patentable because it claims the product and not the process. See In re Thorpe, 777 F.2d 695, 697 (Fed. Cir. 1985) ("The patentability of a product does not depend on its method of production"). It does not follow, however, that once a product-by-process patent issues, it is infringed by any product that would infringe a product claim, as Scripps argues.