Legal Definitions - transition phrase

In patent law, a transition phrase is a specific word or short phrase that connects the introductory part of a patent claim (known as the preamble) to the detailed list of elements or steps that define the invention (known as the body of the claim). This phrase is crucial because it determines the scope of the patent protection, indicating whether the claim is "open" (allowing for additional, unlisted components) or "closed" (strictly limited to the listed components).

Common transition phrases include "comprising," "having," "including," "consisting of," and "consisting essentially of." Each phrase carries a distinct legal meaning that impacts how the patent claim is interpreted and enforced.

• Example 1: Using "Comprising" (Open-Ended Claim)

  Consider a patent claim for a new type of chair:

  "A chair comprising a seat, a backrest, and four legs."

  In this example, "comprising" is the transition phrase. It signifies an "open" claim, meaning that an invention would still fall within the scope of this patent even if it included additional features not explicitly listed, such as armrests, wheels, or a reclining mechanism. As long as the chair has at least a seat, a backrest, and four legs, it could potentially infringe this patent claim. This phrase offers broader protection to the patent holder.

• Example 2: Using "Consisting Of" (Closed-Ended Claim)

  Imagine a patent claim for a specific chemical mixture:

  "A cleaning solution consisting of water, a surfactant, and a lemon scent."

  Here, "consisting of" acts as the transition phrase, creating a "closed" claim. This means the patent protection is strictly limited to solutions that contain *only* these three ingredients. If a competitor's cleaning solution included an additional ingredient, such as a disinfectant or a coloring agent, it would not infringe this specific claim, because it contains more than what is exclusively listed.

• Example 3: Using "Consisting Essentially Of" (Partially Open/Closed Claim)

  Consider a patent claim for a food product formulation:

  "A snack bar consisting essentially of oats, honey, and dried fruit."

  The phrase "consisting essentially of" is a hybrid transition. It means the snack bar must contain oats, honey, and dried fruit, and may also include other ingredients, but only if those additional ingredients do not materially affect the basic and novel characteristics of the invention. For instance, a small amount of a preservative or a vitamin supplement might be permissible without taking the product outside the claim's scope, but adding a significant amount of chocolate chips (which would alter the fundamental character of an "oats, honey, and dried fruit" bar) might not be. This phrase provides a balance between the broadness of "comprising" and the strictness of "consisting of."