Transitional Phrases in Claims

Transitional phrases in patent applications are important, 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 most common transitional phrase used is the “open ended” phrase “comprising”.  However, many claims use “closed-ended” language such as “consisting of”.

Open-Ended

Some applications use open-ended terms such as “comprising” or “which comprises”.  This means that the claim encompasses all the elements listed, but may also include additional, unnamed elements.

For example, if a claim recites elements “A” and “B”, an individual that practices the invention using elements “A” and “B”is infringing, and using “A”, “B”, and a new element “C” is infringing, whereas if she only uses element “A” or “B”, she isnot infringing.

For example:

A therapeutic composition comprising a polynucleotide having the sequence of SEQ ID NO:1.
or,
An expression vector, operable in eukaryotic host cells, which comprises a polynucleotide having the sequence of SEQ ID NO:1.

In these two examples, elements are claimed that include SEQ ID NO:1, but may also include any other unnamed elements; the only restriction is that contains, at least, SEQ ID NO:1. These types of claims may be fairly broad, as any composition that has SEQ ID NO:1 in it would infringe on these claims.

Closed-Ended

Some applications used “closed-ended” claim language, such as the phrase consisting of. The phrase “consisting of” means that the composition (or device, or method) has the recited elements (or steps) and no more.

For example:

A therapeutic composition consisting of a protein having the sequence of SEQ ID NO:2 and a suitable buffer.

This claim covers only the composition of SEQ ID NO:2 and a suitable buffer. If there were any additional elements added to the mixture (that were not defined in the specification as being components of a “suitable buffer”), then the composition would not be covered by that claim.

Combination of Open-Ended and Closed Ended

Often, claims have a combination of open-ended and closed-ended language.

For example:

A recombinant DNA construct comprising a polynucleotide selected from the group consisting of SEQ ID NO:1, SEQ ID NO:2, SEQ ID NO:3, SEQ ID NO:4, and SEQ ID NO:5.

In this claim, the composition must contain at least one of the sequences specified by SEQ ID NO:1 through SEQ ID NO:5, but may also contain any number of additional, unnamed elements. This claim is an example of a Markush Group, which is a type of claim that is common in the chemical arts.