Independent and dependent claims in a patent

Claims in a patent are essentially clauses that define the extent of protection conferred by that patent. Independent and dependent claims in a patent define the boundary or scope of an invention on which protection is sought by applying for the patent. Whether an invention is patentable or not, is decided based on whether the claims are novel and inventive. This means that the claims must capture both novelty and inventive step of an invention. 

A patent application is granted or rejected primarily based on the claims and not based on the description or drawings alone. Additionally, not only from a patent examination’s perspective, the claims in a patent application are also an important deciding factor from a perspective of asserting your patent against an external entity that potentially infringes your patent. You may want to check out this article that describes how are claims used in checking infringement of a patent

What are the types of claims in a patent?

There are several different types of a claims in a patent. However, at a very basic level, you will notice two types of claims – independent and dependent claims.  

What is an independent claim and what is the purpose of dependent claims?

An Independent claim is a standalone claim that captures all the essential features of an invention (or at least an embodiment of the invention) and defines the minimum detail of the invention (or that embodiment) to stand on its own without requiring features from another claim. This means that the claimed invention should at least be able to theoretically function using the features in the independent claim without borrowing features from any other claim.     

An independent claim can be further supplemented by adding dependent claims that add more features (details) to the features covered in the independent claim. Each dependent claim qualifies the independent claim further. 

Let’s take a simple example to understand the above terms. Assume that a chair with 4 legs is invented for the first time and is applied for a patent. If the independent claim covers the chair that has 4 legs (essential elements), a dependent claim may specify that the chair is black (not essential but adds more details). Another dependent claim may specify that the chair is made of wood (another detail). You may have understood by now that for the chair to function, 4 legs may be an essential element which is why it is a part of the independent claim. However, the fact that it is black or is made of wood need not be essential to the functioning of the chair itself. Therefore, these features are covered in the dependent claims. 

There is generally no limit on how many claims you can add except for fee constraints. Most of the patent offices globally allow for some free claims (10 free claims in India; 20 free claims in US) but you have to pay a specified fee beyond that. This is the reason most US patents have up to 20 claims to optimize costs.  

You may want to explore some patents using Google search and read some actual claims in patents to get a better understanding of this concept.

Hope you liked reading the above article. Do comment if you have any questions or comments!