concurring.
I join the opinion of the majority, but I would adopt a different means to interpret the expression “human tissue plasminogen activator” (t-PA). Moreover, I wish to point out an additional reason why I believe that the accused FE1X cannot infringe a claim to t-PA under the doctrine of equivalents.
The independent claims at issue in the ’075 and ’330 recombinant patents contain no definition for the DNA isolate other than that it encodes human t-PA. Such a claim, defining a substance only by its function, encompassing all substances that accomplish that result, is akin to a single means claim, which might fail to satisfy the definiteness requirement of 35 U.S.C. § 112. See Fiers v. Sugano, 984 F.2d 1164, 1171, 25 USPQ2d 1601, 1606 (Fed.Cir.1993). Such a claim avoids that problem only when the term “human tissue plasmino-gen activator” has definitive meaning, when it describes a specific compound. That term is in fact definite, as it is well established that human t-PA is a protein consisting of 527 amino acids. Thus, all the claims which depend upon a definition of human t-PA are limited to that specific compound and any other compounds considered under law as equivalent thereto.* The trial court, of course, held that there was no literal infringement.
Under the doctrine of equivalents, an accused compound can be held to infringe if, inter alia, it represents only an insubstantial change from the claimed compound. See Graver Tank & Mfg. Co. v. Linde Air Prods. Co., 339 U.S. 605, 607, 610, 70 S.Ct. 854, 855, 857, 94 L.Ed. 1097 (1950). The accused compound in this case consists of a protein that contains 446 amino acids, 15% fewer than the t-PA referred to in the claims. This is not an insubstantial change, but a substantial one. Moreover, it has ten times the half-life of natural t-PA. The t-PA recited in the claims was not copied, since the accused FE1X is a very different material, independently invented and developed, requiring an estimated 130 man-years, and costing $20 million. If claims are to have any meaning, as a matter of law such a substance cannot be held to be infringing.
Thus, this case illustrates the problem that results not only when a court fails to construe the claims for the jury, but also when the fact-finder unduly focuses only on the function, way, result analysis of Graver Tank, 339 U.S. at 608, 70 S.Ct. at 856. These limited means of analysis fail to fully elucidate the issue, especially when the patented material is a chemical, as it is here. Is the increased half-life part of the “way” analysis or is it a different “result”? Is the binding to fibrin “function,” as stated by the majority, or is it part of the “way” t-PA dissolves clots? These questions illustrate the shortcomings of the function, way, result tests which relate to “how” a substance works, ie., what it does, rather than what it is, which claims purport to define. The other aspects of Graver Tank, if properly considered by the fact-finder, would have led to a sounder result. The substantiality of the difference between the accused and claimed compounds, the fact of independent development, and the lack of copying, all lead to a conclusion of lack of infringement.
Senior Circuit Judge Cowen agrees with this analysis.