Why do independent claims matter?
If you are applying for a utility patent, it is absolutely critical that you understand how independent claims work. In order for a product or service to be covered by a utility patent, at least one independent claim must be infringed. And infringement means that each element of the independent claim, or its equivalent, is found in the accused product. If none of a patent’s independent claims cover a particular product, there is no infringement.
Ignorance of claims can lead to worthless utility patents. So let’s delve into utility patent claims.
Where are the patent claims?
The patent claims are located towards the end of the written specification. They typically start on a new page after the section entitled Detailed Description of Preferred Embodiments. The top of the page may be marked with the header Claims.
Claims are numbered, so Claim 1 will always be independent.
Which claims are independent?
An independent claim contains a preamble that does not recite another claim number. In contrast, a dependent claim will recite a prior claim number and may, for example, look like:
2. The (device/apparatus/system/method) of claim 1, wherein . . .
In the above example, dependent claim 2 depends upon claim 1.
What is the scope of an independent claim?
In order for a product to infringe an independent, the product must contain each and every element of the independent claim. If an element is missing in the product, there is no literal infringement, but there still might be infringement under the doctrine of equivalents. So, it’s important to explore whether the product has the equivalent of a missing claim element.
What is a dependent claim?
A dependent claim hangs from an independent claim and recites further features or limitations. In other words, a dependent claim gets more specific and, thus, narrower in scope.
A dependent claim often recites features that might be considered secondary, while the independent claim usually recites a combination of primary features. In other words, the independent claim will typically include a combination of core features. Secondary features that may be considered nice to have, but not critical, are often written into the dependent claims.
What is a claim set?
A claim set consists of a single independent claim and all the dependent claims that depend upon that particular independent claim. To illustrate, there are two claim sets in the following example:
- An apparatus, comprising …
- The apparatus of Claim 1, further comprising . . .
- The apparatus of Claim 2, wherein . . .
- An apparatus, comprising . . .
- The apparatus of Claim 4, further comprising . . .
- The apparatus of Claim 4, wherein . . .
In the above example, Claims 1 and 4 are independent. Also, notice how dependent Claim 3 depends upon dependent Claim 2, which means that the scope of Claim 3 includes everything recited in both Claims 3, 2 and 1.
In contrast, dependent Claim 6 depends directly upon independent Claim 4. So the scope of Claim 5 contains everything in Claims 6 and 4 (but not Claim 5).
How do patent examiners review claims?
In each claim set, patent examiners start with the independent claim by looking for each claim element in the prior art. If the examiner can find all the elements in the independent claim, the examiner will reject the independent and move onto the dependent claims.