The claims in a patent define the scope of the invention and therefore set the parameters for the right to exclude others from making, using or selling in the United States or importing into the United States.1 Every non-provisional patent application must


FIGURE :Independent and dependent claims.

conclude with one or more claims that particularly point out and distinctly claim what the applicant regards as his invention.2 Claims can be of two types: independent or dependent. Independent claims stand alone, whereas dependent claims rely on the claim they are dependent from. It is important that a dependent claim borrows all of the limitations from the claim it is depending from and adds at least one additional limitation or further restricts a limitation that is already present. To illustrate, a sample claim set is provided in Figure below.

sample claim set

FIGURE :Alternative claim set.
In this example claim set, claim1 is independent since it does not depend from any other claim—the claim stands alone. In contrast, you can see that the claims 2 and3 are each dependent, they incorporate the terms of another claim and then provide further limitation to the claim that they are dependent from. Whereas independent claim 1 allows selecting a compound with a possibility of 3 different groups at ‘X,’dependant claim 2 allows only one (hydrogen); so dependent claim2is narrower than claim 1 that it depends from. Finally, claim 3 depends from claim 2, meaning that it incorporates all of the definitions from claim 2 and then provides a further limitation.

As a result, the compound of claim 3 will have the compound of formula I as definedin claim 1 except that X and Y are both set to hydrogen.

A simpler but equivalent way of presenting these three claims is illustrated in Figure below. The Markush structure is not repeated because it is understood that the dependent claim is importing the entire Markush that it is dependent from, and then further limiting that structure according to the specified language.

Having additional or further narrowing limitations means that the dependent claim is necessarily narrower in scope.Adependentclaimthatis in any way broader than the claim it depends from is not properly dependent. For example, by slightly modifying the claim set just presented, we have converted claim 2 to an improper dependent claim (Figure below). Even though claim 2 is narrower overall, it still is improper for attempting to expand the definition of X to include the group -OH.


FIGURE :Claim set with improperly dependent claim.

As a practical matter, understanding the difference between an independent and dependent claim can save time when examining issued patents to understand their claim scope. Specifically, if you are examining an issued patent to determine whether a certain compound, activity, etc. falls within the scope of the patent claims, you need only examine the independent claims. Why? Because the dependent claims cannot be broader in any sense than the independent claims they are dependent from. Accordingly, if you are outside the boundaries of the independent claims, you also will be outside the boundaries of any of the corresponding dependent claims since those claims are completely within the broader boundaries of the independent claims. Likewise, if you are evaluating a set of claims to determine how a piece of prior art might affect the novelty of those claims, you should examine the novelty of the independent claims of interest first. If the independent claims are novel, then the claims that are properly dependent from those claims are presumed novel as well. Notwithstanding, this all assumes that the claims were properly drafted. If the analysis is sufficiently important, one should carefully review the independent claim sand review the dependent claims to make sure they are not broader in scope.

You may ask,Why bother to include dependent claims in the first place? If someone is infringing a dependent clamshell also be infringing the independent claim from which it is derived. There are at least a few practical reasons. First, it is often easier for someone in the future to try to have your broadest claims declared invalid for a lack of novelty or for being obvious; broader claims are more likely to read on the prior art because they occupy more turf. Second, it is generally harder to enable one to “make and use” a broader claim because a patent claim needs to be enabled throughout its scope; a broader claim will require more enablement. If a claim is not enabled, then it is invalid because it fails to meet the written description requirement. Finally, the existence of a dependent claim serves to emphasize that the independent claim from which it depends is not so limited. For example, consider the following claims:

  1. Compound A or derivatives there of.

  2. The calcium salt of compound A.

The existence of dependent claim 2 points out specifically that claim 1 includes salt forms. This is important because in some instances, claims might be read more narrowly then the drafter intends. The use of dependent claims helps more clearly define the breadth of the claim it is dependent from as well as provide additional,narrower protection.

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