Cooper v. Goldfarb,  47 U.S.P.Q.2d 1896, 1998 WL 550259 (Fed. Cir. Sept. 1, 1998).



1. Whether a junior party has priority of invention when he files a patent for the same invention as a pending patent, the senior party has prior conception but a later reduction to practice, and when the senior party does not prove that he exercised diligence to achieve reduction to practice.

2. Whether a junior party can prove a reduction to practice by a preponderance of the evidence when there is no evidence in the contemporaneous research record that supports the junior party's personal testimony, but only the corroboration of witnesses that state that he "had in mind a structure that corresponded to what was needed for reduction to practice." Cooper, 1998 WL, at *6.


1. Yes.  The junior party has priority of invention.

2. Yes.  A junior party can prove a prior reduction to practice by a preponderance of the evidence.


The patent is for expanded polytetraflouroethylene (PTFE) artificial vascular grafts that are flexible membranes.  After the PTFE is stretched, there are nodes of PTFE connected by thin PTFE fibrils.  It is important to have a length between the nodes of the fibers that is long enough to permit tissue growth into the walls of the graft, but short enough to prevent excessive bleeding through the graft walls.  The dispute centers around the question of who was the first to recognize the significance of the length between the fibers and the first to reduce the invention to practice by performing a successful experiment.

Cooper's research team was determined by the Board of Patent of Appeals and Interferences (the Board) to have conceived the invention by June 5, 1973.  On that date, Cooper, the plant manager of W.L. Gore & Associates (Gore), told a Gore manufacturing engineer that there was a need for sufficient internodal separation in order to allow tissue ingrowth.  Goldfarb did not prove conception prior to Cooper.  Goldfarb's conception was determined by the Board to be by July 1973, based on the testimony of Goldfarb that is corroborated by two Gore employees.

On April 22, 1973, Cooper's research team harvested two successful grafts out of four grafts placed in a test subject.  The Board determined this not to be a successful reduction to practice because there was no corroborated evidence that the successful grafts were within the parameters of the required internodal length.  On the other hand, the Board found Goldfarb to have successful reduction to practice by July 1973.  This is based on Goldfarb's testimony, corroborated by two witnesses, that he measured the internodal lengths of the successful grafts and realized that the lengths were within the desired amount.  Cooper's reduction to practice was determined by the Board to be after July, 1973.

The court followed the rule that "priority of invention goes to the first party to reduce an invention to practice unless the other party can show that it was the first to conceive of the invention and that it exercised reasonable diligence in later reducing that invention to practice." Cooper, 1998 WL, at *4.  The court found that Cooper did not provide evidence which would prove a reduction in practice prior to July 1973 and that Cooper's patent filing date, a constructive reduction to practice, on April 2, 1974, was after Goldfarb's actual reduction to practice.  As for the evidence supporting Goldberg's reduction to practice, the court found that "circumstantial evidence provided sufficient corroboration," to prove a reduction to practice in July, 1973.  The court did not require that "each individual act in the reduction to practice of a count must be proved in detail by an unbroken chain of corroboration."  Also, "[i]n the final analysis, each corroboration case must be decided on its own facts with a view to deciding whether the evidence as a whole is persuasive." Berges v. Gottstein, 618 F.2d 771, 776, 205 U.S.P.Q. 691, 695 (C.C.P.A. 1980).

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