The Patent Light

A patent is a bargain an inventor makes with the government.  The inventor increases public knowledge by disclosing the invention.  In return, if the U.S. Patent and Trademark Office (“USPTO”) believes that invention meets the statutory requirements, the inventor receives a monopoly as defined by the claims of the patent.  Thus, patents may be thought of as having two parts: (1) a specification (and drawings) which contain the patent holder’s discloser or contribution to the public knowledge, and (2) the claims which define the scope of the quasi-monopoly granted to the patent owner by the government.

Patent claims should be very precise so that the public has adequate notice of the exact scope of the monopoly. For this reason, claims are often written in an arcane legal language designed to specify the exact limits of the grant of monopoly – at least that is the theory.

In reality, patent claims are hard to read, harder to write and even harder to fully understand.  Unfortunately, it often takes years of legal training to fully understand the scope of patent claims because U.S. courts have held that claims do not always mean what they say.  In other words, to interpret the scope of the claims, one must often rely on more than just the “plain and ordinary meaning” of the claim language.

Courts have established legal doctrines which have both expanded claim breadth and have decreased claim breadth.  So, to interpret the proper claim scope for any given claim, several sources are usually analyzed and several legal doctrines are usually applied.

To determine the meaning of a claim, the “plain and ordinary meaning” of the claim terms are consulted first.  In fact, the preference is to use the plain and ordinary meaning of the claim terms when possible.  However, if the patentee used the claim terms in one way to obtain the patent, it would be fundamentally unfair for the patentee to be allowed to use the claim terms in a very different manner against potential infringers or competitors.

To check for consistency, the “plain and ordinary meaning” of the claim terms are compared to the usage of the claim terms in the patent specification.  Often, the claim terms will be defined in the specification or used in ways which will limit the scope or define the meaning of the terms in unique ways.

Next, the patent prosecution history will be consulted.  The patent prosecution history is the record of the back and forth negotiation with the USPTO to arrive at the issued claims.  In many situations during prosecution, the applicant will make statements or arguments which can be used later to define or limit the scope of the claims.  Again, the theory is that the patentee should be consistent in his/her usage of the claim terms.

Sometimes, other related patents or patent applications owned by the patent owner may also be consulted to see if similar terms were defined in these applications.  This is especially true when the patent in question is but one of a family of patent applications.

Finally, if the claim terms are not defined well in the patent specification and prosecution history, outside sources or extrinsic evidence such as industry dictionaries or reference materials (published around the time of the patent filing) may also be consulted in certain situations.

Furthermore, patent claims are presumed to be valid.  So, if a claim element can be interpreted in two different ways and one of those ways will invalidate the claim due to prior art, the claim element will be interpreted in such a manner as to uphold the validity of the patent.

On top of all this, certain judicial doctrines are often applied to the claim scope.  For instance, under the doctrine of equivalents, certain patent claim terms may be broadened to include their “equivalents.”  As an example, if the claim uses a nail, it is possible that a product that uses a screw might also infringe on the claim if the screw performs the same function as the nail, in the same way to achieve the same result.  In yet other situations, the claim scope may be narrowed.  For instance, if narrowing amendments to the claims were made during prosecution to overcome prior art references, the patent owner loses right to assert the doctrine of equivalents for the amended claims.  So, it is often necessary to review the history of claim amendments to determine which claim terms were amended during prosecution.

So, reading the patent claims is only the first step in determining claim meaning.  In fact, in patent litigation, a judge must construe the disputed claim terms before trial in what is called a “Markman Hearing” or “Claim Construction Hearing.”  During a Markman hearing the judge examines evidence from all parties on the appropriate meanings of relevant key words used in a patent claim, when patent infringement is alleged by a plaintiff.  Often, a Markman Order will determine the outcome of a case and force settlement if the judge interprets the claim terms in a narrowing manner so that no infringement is possible.

To sum, and at the risk of oversimplification, when interpreting patent claims, look to the plain and ordinary meaning of the claims first, then review the specification to see if the claim terms have been defined in the specification, then review the prosecution history of the patent (and any related patents).  Finally, you should apply the doctrine of equivalents to determine the exact scope of the claim breadth on any claim terms which were not amended during prosecution.

This is a confusing subject.  If you have questions, feel free to contact Bill Naifeh at www.naifehlaw.com.