Insituform v. CAT Contracting (Fed. Cir. 2004).
Underground pipes, such as sewer pipes, are often subject to great stress. As a result, over time, the pipes develop cracks and other structural defects, which can result in leakage. In the past, the only way to rehabilitate a section of underground pipe was to dig up the broken section and replace it. Eric Wood pioneered a process for rehabilitating underground pipe without digging it up. He patented his invention and sued several companies for infringement. The case has been ongoing for nearly fourteen years, and included an appeal to the Supreme Court.
During prosecution, plaintiffs made amendments to the claims. The question in this rehearing was whether the plaintiffs have rebutted the Festo presumption that a narrowing amendment made for a reason of patentability surrenders the entire territory between the original claim limitation and the amended claim limitation. The Federal Circuit found that the presumption had been rebutted. “We reach this conclusion because we conclude that the prosecution history establishes that “the rationale underlying” the amendment narrowing the scope of literal claim coverage from multiple cups to a single cup bears “no more than a tangential relation to the equivalent in question.”
[T]he narrowing amendment in this case was for the purpose of distinguishing the invention over Everson. Insituform made it clear that the difference between its process and Everson was that its process did not have the disadvantage of the Everson process of a large compressor at the end of the liner. There is no indication in the prosecution history of any relationship between the narrowing amendment and a multiple cup process, which is the alleged equivalent in this case. Thus, we hold that plaintiffs have successfully rebutted the Festo presumption by establishing that the amendment narrowing the claimed invention from multiple cups to a single cup was tangential to accused Process 1, which used multiple cups attached at different points along the liner tube. We therefore affirm the judgment of infringement under the doctrine of equivalents.
Accordingly, the Court affirmed the judgment that the accused process infringed the claims under the doctrine of equivalents.
What is the Festo Presumption: During prosecution of a patent application, the Applicant may make amendments that narrow the scope of the claims. Under ordinary circumstances, the court’s will presume that these amendments were made for a reason of patentability, and will not allow any allegations of infringement of “equivalent” structures — because claims to equivalents were relinquished through the amendment. The presumption can be rebutted by showing that the amendment only bears a tangential relation to the equivalent in question.