Patent It Yourself - PDF Archive

ChaPter 15 | After Your PATENT ISSUES: Use, MAINTENANCE, and INFRINGEMENT | 423
have to do some research. Use an Internet search engine
such as Google or Copernic, or consult a librarian in the
Business department of a good library, and find out all you
can about the infringer and the infringing product. There
are services such as Bitpipe.com that have sales figures for
various products and can research them. Also investment
advisories and research companies such as Hoover’s, Value
Line, etc., can also provide many sales figures. A business
school professor may be able to provide suggestions. You may
have to spend several days and travel down many avenues to
get enough information to present to the litigator.
Step 4: Apply the Doctrine of Equivalents
The law, recognizing that humans aren’t perfect, formerly
provided an out if the essence of an invention was copied,
but the claims weren’t literally infringed. Under the doctrine
of equivalents (DoE), even if each element of a patent’s claim
is not literally met by an element of the device, so long as
the element of the device is the “equivalent” of the claimed
element, the device can still infringe that element. A device
element is equivalent if it performs the same function in the
same way to achieve the same result as the claim element,
or the role of the device element is substantially the same as
that of the claim element. However, the DoE was severely
limited by the U.S. Supreme Court on 2002 May 28 in Festo
v. Shoketsu, 535 U.S. 722 (2002). Under Festo, if the patentee
amends a claim in any way during prosecution to make it
allowable (this is almost always the case), the DoE can’t be
used with that claim unless the patentee can show that the
narrowing amendment did not surrender the particular
equivalent in question—that is, if the particular equivalent
is not related to the way the claim was amended or was not
foreseeable at the time. Also, if the court can’t determine the
reason for the amendment, the DoE will not be available.
Even without Festo, the DoE did not apply if “file wrapper
estoppel” (also known as “prosecution history estoppel”)
exists—that is, the claim element was amended during
prosecution to define over prior art.
EXAMPLE: Minerva Murgatroid of San Francisco has a
patent on a mechanism for bunching broccoli. Its main
claim recites the mechanism, including a recitation that
the broccoli is banded with a wire-reinforced paper band.
She didn’t claim the band more broadly because she
didn’t read Chapter 9 and think to do so, this being the
only type of band that would work at the time she got
the patent.
A few years later, LeRoy Phillips of Philadelphia discovers
a plastic broccoli band that will work just as well as Minerva’s
wire-reinforced band. He makes broccoli-banding machines
and sells them, with his plastic bands, to Fred Farmer, who
uses them to band broccoli on his farm in Fresno. Minerva
can sue either LeRoy in Philadelphia or Fred in Fresno. Even
though her main claim doesn’t literally read on LeRoy’s
machine—that is, describe all of its physical elements—she
can win the infringement suit using the DoE, provided she
didn’t amend her claims during prosecution so as to invoke
the Festo doctrine. LeRoy’s plastic band is equivalent in
structure, function, and result to the wire and paper band,
the band material being a relatively minor change that won’t
get LeRoy or Fred off the hook.
However, suppose during prosecution of her patent
application before the PTO, Minerva originally had broad
claims to any type of band but then narrowed them to the
wire-reinforced paper band to avoid a prior-art reference.
In this situation Minerva is subject to the doctrine of file
wrapper estoppel and may not use the DoE to rebroaden
her claim. Even if Minerva merely amended her claims to
make them clearer, under the Festo doctrine, she can’t use
the DoE.
The Negative Doctrine of Equivalents
There’s a rarely used converse of the doctrine of equivalents,
the so-called negative doctrine of equivalents.
Under this, even if your claims literally read on the infringing
device, but the infringing device has a different
structure, function, or result than your invention, the
device may be held not to infringe.
Step 5: Consider Whether a Contributory Infringement
Has Occurred
If your claims don’t read on the infringing device, but the
infringing device is a specially made component that’s only
useful in a machine covered by your patent, the infringer may
be liable under the doctrine of contributory infringement.
EXAMPLE: In the example above, LeRoy makes an
entire broccoli-banding machine like Minerva’s, except
that he doesn’t sell or supply any bands. Minerva’s
claims don’t literally read on LeRoy’s machine since her
claims recite the band. Nevertheless, Minerva can bag
Fred under the doctrine of contributory infringement,
since his broccoli-banding machine is useful only in the
mechanism of Minerva’s patent claim and since it has no
other noninfringing use.
Under new legislation, if a patent holder sues to enforce
a method or process claim, a defendant can escape liability