In the world of patents, precision and clarity are paramount. Patent claims serve as the backbone of a patent application, defining the scope and boundaries of an invention. Transition phrases play a crucial role in establishing the extent of protection granted by a claim. In this post, we delve into the basic rules for transition phrases, focusing on the somewhat less commonly used term "consisting of."
But first a refresher on understanding transition phrases: Transition phrases are used in patent claims to convey the relationship between the elements of an invention and are the break between the preamble, and the body of the claim. They help define the scope of protection by signaling the inclusion or exclusion of certain elements. The three commonly used transition phrases are summarized bel:
"Comprising": When a claim includes the term "comprising," it means that the invention encompasses the listed elements, but may also include additional elements not specifically mentioned in the claim. This term allows for flexibility and permits the presence of additional components or steps.
"Consisting of": On the other hand, the term "consisting of" in a claim signifies that the invention consists solely of the elements listed in the claim. It excludes any additional elements, regardless of their obviousness or practicality. This phrase creates a narrower scope of protection by limiting the invention to the exact elements mentioned.
"Consisting essentially of": This transitional phrase strikes a balance between the flexibility of "comprising" and the specificity of "consisting of." When a claim contains the term "consisting essentially of," it means that the invention includes the listed elements and any other elements that do not materially affect the basic characteristics of the invention. It allows for minor variations or additions that do not substantially alter the invention's core functionality.
However, when these terms are used outside of the preamble, things can get confusing. While the term "consisting of" typically limits the scope of a claim, there is a notable exception when it appears in the body of the claim. In this particular case, "consisting of" does not restrict the addition of further elements to the claim. Instead, it solely limits the particular element mentioned after the phrase.
This rule ensures that the listed element remains indispensable to the invention while allowing the claim to encompass additional elements that may enhance or complement the listed element. By permitting the inclusion of supplemental components, this exception provides flexibility to the claim drafter.
To see how this plays out in the real world, consider Appeal 2022-002519, Application 16/369,911. This Applied Materials invention relates to to a fluid delivery system for use with a semiconductor process chamber that comprises a number of 3-way valves that aid in the elimination of dead space in the fluid delivery system. Claim 1 is reproduced below (emphasis added):
1. An assembly, comprising:
a process chamber;
a process fluid delivery system coupled to the process chamber, the process fluid delivery system having a plurality of process fluid sources and a plurality of three-way valves, and consisting of one three-way valve per process fluid source, wherein the process fluid delivery system includes:
a process fluid conduit;
a divert conduit;
a first three-way valve of the plurality of three-way valves coupled to a first conduit and a second conduit, wherein the first conduit is coupled to the process fluid conduit and the second conduit is coupled to the divert conduit;
a second three-way valve of the plurality of three-way valves coupled to a third conduit and a fourth conduit, wherein the third conduit is coupled to the process fluid conduit and the fourth conduit is coupled to the divert conduit;
a third three-way valve of the plurality of three-way valves coupled to a fifth conduit and a sixth conduit, wherein the fifth conduit is coupled to the process fluid conduit and the sixth conduit is coupled to the divert conduit; and
a purge gas valve coupled to a seventh conduit, wherein the seventh conduit is coupled to the process fluid conduit
In dispute between the examiner and the applicant was whether the scope of the claim 1 language “consisting of one three-way valve per process fluid source” limits the number of three-way valves in the process fluid delivery system. The examiner relied on the “comprising” in the transition phrase and the “having” in the claim element to determine that additional 3-way valves could be included. The applicant, on the other hand, argued that the “consisting of” language limited the system to one 3-way valve per fluid source. Notably, the examiner did not make a 112 clarity rejection, since the examiner considered that the interpretation was reasonable.
The PTAB found that the claim was unclear. From the decision (internal citations omitted):
Here, the ordinary artisan cannot determine the metes and bounds of the claims because it is not clear what is excluded by “consisting of.” Use of “consisting of” within the body of a claim, rather than immediately following the preamble, closes only the element preceded by “consisting of,” and does not negate the open nature of a “comprising” transition present in the claim between the preamble and body. Claim 1 requires “a process fluid delivery system . . consisting of one three-way valve per process fluid source.” The process fluid delivery system is the element preceding “consisting of” and it is the process fluid delivering system that we would normally interpret as closed to unrecited process fluid delivery structures. But that interpretation would conflict with the rest of the claim, which requires other process fluid delivery structures, i.e., process fluid delivery conduits and a purge gas valve. It appears that Appellant intends to merely exclude other three-way valves from the process fluid delivery system. But such an interpretation of “consisting of” would conflict with our reviewing court’s interpretation of the term. As drafted, it is unclear what claim element is limited by the phrase “consisting of ” and how it is to be interpreted. Therefore, the claim is indefinite.
By understanding the distinctions between "comprising," "consisting of," and "consisting essentially of," and by understanding how these phrases change scope of claims depending on where they are positioned within the claim, inventors and patent practitioners can accurately convey the intended breadth or specificity of their claims. When "consisting of" is used in the body of the claim, practitioners should take care to structure the claim and use the term so that there are no inconsistencies when properly interpreting the claim.