Twenty-Year-Old Festo Case Propelled To Its "Foreseeable" Conclusion

In a case that has been twice to the U.S. Supreme Court and twice to the en banc Federal Circuit in its almost 20-year odyssey, a split panel of the U. S. Court of Appeals for the Federal Circuit has now held that since the accused structure was, in view of prior art provided to the U.S. Patent and Trademark Office (USPTO), foreseeable at the time the patent owner amended its claims, prosecution history estoppel applied and the accused structure was surrendered (as an equivalent) by amendment. Festo Corp. v. SMC Corp., Case No. 05-1492 (Fed. Cir., July 5, 2007) (Dyk, J.; Newman, J., dissenting).

Festo owns a patent directed to a magnetically coupled arrangement for a driven member and a driver member that claims a "small gap" magnetically coupled rodless cylinder. The piston/cylinder was a known (prior art) device for magnetically coupling a driving member to a driver member. The difference between the Festo invention and the prior art was that the gap between the piston and driven