Transitional Term in a Patent Claim


Transitional term in a patent claim contain only three main components, a preamble, a transitional term such as “comprising” (or some other transition phrase) and a body. That is, the transitional term is the word between the preamble and the claim body. Transitional terms in patent applications are important and materially affect the claim, as they specify whether the claim is limited to only the elements listed, or whether the claim may cover items or processes that have additional elements.

The transitional terms acts as a limitation on the claim, indicating whether a similar device, method, or composition infringes the patent if it contains more or fewer elements than the claim in the patent. It may be understood that almost all terms and language used in constructing a claim specifically narrows or broaden the scope of the patent. The determination of what is or is not excluded by a transitional term must be made on a case-by-case basis in light of the facts of each case.

There are three kinds of transitional terms: open, closed, and semi-open. These three kinds of transitional terms give different scope of protection to the claim. The open transitional term means that the elements do not exclude other elements that are not recited in the claim. The closed transitional term means that any of the other elements that are not recited in the claim shall be excluded from the interpretation of the claim scope. The semi-open transitional terms lies somewhere in the middle of the other two kinds, and is usually subjected to interpretation based on specification, patent history, among others.

  • Open transition:

The most common transitional term used is the open ended phrase “comprising”. “Comprising” is a term that is often used in claim language and means that the named elements are essential, but other elements may be added and still form a construct within the scope of the claim. In effect, “comprising” is a shorthand way of saying “including the following elements but not excluding others.” In general, a patent attorney drafts claims containing a minimum number of elements that will function in a combination and uses the open term comprising in order to cover the invention as broadly as possible under the patent. This is the broadest form of transition, as it does not limit the preamble to whatever elements are identified in the claim. The transitional terms “including,” “containing,” or “characterized by,” are synonymous with “comprising” and are also inclusive or open-ended. These also do not exclude additional, not recited elements or method steps.

  • Closed transition:

A closed transition phrase is often avoided by patent attorneys, but is sometimes required considering the claim drafting requirements. The closed transitional term usually uses the words “consisting of”. The use of closed transitional phrase essentially limits the preamble to only the elements that are described in the claims and nothing else. Therefore, use of such transitional term may possibly allow a competitor to copy and manufacture the patented product without essentially infringing it, if the competitor makes even a minor improvement/addition to the invention as recited in the claim. That said, the closed transitional phrase are sometimes required as it may assist with overcoming a close prior art.

  • Semi-open transition:

A third kind of transition, the semi-open (or hybrid) transition, usually involves the use of the phrase “consisting essentially of”. This kind of transitional term keeps the claim “open” to include additional elements, as long as those additional elements do not significantly or materially affect the novel characteristics of the claim. This kind of transitional term helps with avoiding prior art, and on the other hand is generally broad enough to thwart the possible infringers to blatantly copy and practice the invention.

There are other transitional terms, such as “having” which must be interpreted in light of the specification to determine whether open or closed claim language is intended.

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