A patent specification includes a set of claims. The claims define the scope of protection that is sought. The specification also includes unclaimed subject matter described in other sections of the application. There are several key concepts to remember regarding unclaimed subject matter.
First, unclaimed subject matter is still prior art. For a later applicant, this means that unclaimed subject matter described in an earlier application may be relevant to patentability. For a patentee, this means that other parties, including competitors, cannot obtain patent protection for inventions that are anticipated or obvious in view of the unclaimed subject matter.
Second, unclaimed subject matter may be pursued in a continuing patent application as long as the first application is still pending. Continuing patent applications include continuation applications, divisional applications, and continuation-in-part (CIP) applications. This means that after allowance, unclaimed subject matter should be evaluated to determine if additional patent coverage is desired. A published patent application should also be similarly evaluated before abandoning the application.
After a patent is granted, unclaimed subject matter belongs to the public domain. Subject matter in the public domain cannot be patented by any party.
Hypothetical: A is granted a patent. The patent specification describes an incadescent lightbulb with a carbon filament or a tungsten filament. Only the carbon filament is claimed. No continuing application is filed.
Ex. 1: Applicant B attempts to obtain a patent on a lightbulb with a tungsten filament to prevent A from producing tungsten filament light bulbs. The Patent Office rejects B’s application, citing A’s patent.
Ex. 2: Applicant C attempts to obtain a patent on a lightbulb with a molybdenum filament. The Patent Office argues that C’s invention is obvious, citing A’s patent and another reference that states that molybdenum is often used as a substitute for tungsten. C must now present arguments that the substitution was not obvious.