The Festo decision posed a threat to the US doctrine of
equivalents, or DOE. This doctrine has been relied upon for years
by patent owners to stop copycat products that use technology
similar to their original. Basically, the doctrine says that if a
product or process is not substantially different from the elements
of a patented invention, it is considered to be infringing.
Festo Corporation is a robotics company in Long Island, New
York. It challenged a Japanese rival, Shoketsu Kinzoku Koygo
Kabushiki, alleging patent infringement. The federal court ruled
that there was no infringement. Significantly, it added that Festo
lost certain rights in its technology as soon as it narrowed its
original claim for a patent.
Until the Festo case, elements of an invention stripped from a
patent claim during amendment were still considered the property of
the inventor under US law, even if they did not appear in the
formal patent description. The implications of this change in the
law could be huge. Very few US patent applications succeed without
some degree of amendment.
Lawyers for some patent owners say that Festo opened the door to
copycat products. They also warn that it will add to the expense of
securing and protecting a patent. These arguments are disputed by
some other patent lawyers. One opponent is patent lawyer Sean
Johnston, quoted last year in business magazine Red Herring: "Is it
really an invention in the first place if you don't grasp the full
scope of it, had to amend your claim, or use DOE to protect it? I
don't think so."
