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18 PATENTLAWVarious adjustments and extensions may be available un-
der certain conditions. A discussion of these conditions
is beyond the scope of this chapter, however. The patent
terms discussed here pertain to U.S. utility and plant
patents. U.S. design patents expire after 14 years from
the issue date.How to Read a Patent
A patent is organized into several sections. These include
a cover sheet, drawings, a specification and claims. The
specification includes a background, a summary, a brief
description of the drawings, and a detailed description.
The cover sheet includes bibliographical information, a
short abstract that briefly describes the invention, and
usually a copy of one of the drawings considered to be
representative of the invention. Drawings must be pro-
vided where necessary for understanding the invention.
The background section describes prior art, or the state
of the art prior to the patented invention. The summary
provides a short synopsis of the invention and often is a
regurgitation of the claims in plainer language than the
claims. A brief description of the drawings typically fol-
lows. Next comes a written description (often labeled as a
detailed description) of one or more embodiments of the
invention. As previously mentioned, the written descrip-
tion must enable any person skilled in the art to make
and use the invention. The description must also set forth
the “best mode” contemplated by the inventor, although
this best mode need not be pointed out as such. Finally,
a set of claims is provided which point out and distinctly
claim the protected subject matter. Each claim is written
as a single sentence and typically consists of a preamble, a
transitional phrase, and a set of limitations. For example,
Claim 1 of U.S. Patent No. 6,004,596 (“Sealed crustless
sandwich”) appears as follows:I claim:- A sealed crustless sandwich, comprising:
a first bread layer having a first perimeter surface
coplanar to a contact surface;at least one filling of an edible food juxtaposed to
said contact surface;a second bread layer juxtaposed to said at least
one filling opposite of said first bread layer,
wherein said second bread layer includes a
second perimeter surface similar to said first
perimeter surface;a crimped edge directly between said first peri-
meter surface and said second perimeter surface
for sealing said at least one filling between said
first bread layer and said second bread layer;wherein a crust portion of said first bread layer
and said second bread layer has been removed.Thepreambleis the phrase: “A sealed crustless sand-
wich.” Thetransitional phraseis “comprising.” These arefollowed by five limitations: “a first bread layer,” “at least
one filling,” “a second bread layer,” “a crimped edge,”
and the condition “wherein a crust portion...hasbeen
removed.” For this claim to be infringed, an unauthorized
party must make, use, sell, or offer to sell or import into
the United States a sandwich product that satisfies every
one of these limitations. It is irrelevant that a crustless
sandwich may have other components not described in
the claim, for example, a cherry on top. As long as some
food product meets every one of the limitations listed
in Claim 1, that product is said to infringe Claim 1. On
the other hand, if a sandwich is lacking some element,
such as the crimped edge, it cannot literally infringe (but
see the subsequent discussion regarding the doctrine of
equivalents).
A first claim is typically written broadly to cover a wide
range of variations. Narrower claims often follow that in-
clude the limitations of the broad claim, plus additional
limitations that limit the scope of the invention recited by
these narrower claims. Narrower claims are often written
as dependent claims.
For example, Claim 1 above is an independent claim.
Claim 2 in the same patent reads:- The sealed crustless sandwich of claim 1,
wherein said crimped edge includes a plurality of
spaced apart depressions for increasing a bond of
said crimped edge.
Claim 2 is called a “dependent” claim because itde-
pends fromClaim 1, that is, it includes all of the five lim-
itations of Claim 1, plus the further limitation that the
crimped edge include “spaced apart depressions.” For a
sandwich to infringe this claim, it must meet all of the
limitations of Claim 1andClaim 2. One reason for pro-
viding additional narrower claims is that often, during
litigation of a patent suit, some claims may be found to
be invalid. Even though a claim may be invalidated in a
court of law (for example, if a publication is presented
that predates the patent’s priority date and that teaches
or suggests one or more of the claims), a narrower claim
with additional limitations may still be valid, even if it
depends from the invalidated claim.
Another reason for providing additional narrower
claims is the so-called doctrine of claim differentiation,
under which “two claims of a patent are presumptively
of different scope” (Kraft Foods, Inc. v. Int’l Trading Co.,
2000). According to this doctrine, if a dependent claim
includes a narrowing definition of some limitation of a
base claim, then the base claim is presumed to encom-
pass not only the narrow definition, but other embodi-
ments as well. For example, Claim 2 may help to support
the proposition that Claim 1 covers crustless sandwiches
that do not have depressions that are spaced apart as well
as crustless sandwiches that have other kinds of bonding
mechanisms.
First-time readers of claims are often puzzled by the
seemingly bizarre language and grammar used in claims.
Sometimes this language results from the statutory re-
quirement that claims particularly point out and distinctly
claim the subject matter that the inventor or applicant re-
gards as his or her invention. Thus, use of a definite article