Homework 26: Case on Doctrine of Equivalence

Valmont Industries Inc. v. Reinke Manufacturing Company Inc. (1993)

(983 F.2d 1039)

This case concerns an adaption for center-pivot (i.e. rotating) irrigation systems. The adaption (an apparatus that attaches to the main frame of the sprinkler) allows the corners of a field, normally missed by the standard rotating irrigation system, to be watered. The infringement issue relates to the means by which the position of the sprinkler is detected, relative to the field. The patent uses a method of pivot angle encoders, while the "infringing" patent uses buried electromagnetic cables to guide the sprinkler around the field.

The CAFC ruled that the second device was not infringing, reversing the decision of the district court. The district court argued that the means of controlling the system were equivalent. The CAFC's argument was that while the two irrigation systems performed substantially the same overall function to obtain substantially the same overall result as the claimed invention, the way those results were achieved was substantially different. "Comparison of these two control means compels the conclusion that the claimed control means and Reinke's control means are not structurally equivalent.[...][E]ven though both the control means in the specification and the control means on Reinke's device use electric signals, the structures generating those signals are strikingly different."

Because the doctrine of equivalence requires that the two devices perform substantially the same function in substantially the same way to achieve substantially the same results, the two control systems were not equivalent under the doctrine of equivalence because they did not meet the "way" requirement of the doctrine of equivalence.