A dependent claim is a claim presented in a patent or patent application filed with the USPTO that refers back to and further limits one or more of the proceeding claims. If a dependent claim broadens the scope of the claim from which it depends, it is considered an improper dependent claim and will result in a rejection being issued by the Examiner. Further, a dependent claim incorporates all of the limitations of the claim or claims from which it depends.
In a majority of cases, a dependent claim will refer back to an independent claim; however, it is entirely proper for a dependent claim to refer back to another dependent claim.
In the following example, claim 2 is a dependent claim that depends from independent claim 1. Specifically, claim 2 includes all of the limitations of claim 1 and the limitation recited in claim 2.
Why do you use dependent claims?
When drafting the claims of a patent application, the goal is to define your invention as broadly as possible to encompass the greatest scope of protection around your invention. This broad protection is often sought within the independent claims and then further narrowed, thereby further defining the scope of the invention and claim potential design arounds by competitors.
Additionally, there is a significant cost benefit to strategically using dependent claims when drafting a patent application. For example, you may file up to three (3) independent claims and twenty (20) claims total (dependent and independent) without incurring additional government fees. Thus, a majority of patent applications have 1 – 3 independent claims and 17 – 19 dependent claims for a total of twenty (20) claims.