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September 17, 2006

Dependent Claim Koan

What is the value of a dependent claim whose limitations are anticipated by the prior art? Considering the current obviousness standard, most recently enunciated in Alza v. Mylan, is there good reason to assert, or even draft, such dependent claims? After all, if the independent claim is done in by prior art during litigation, the dependent claim practically falls as well. Comments welcome.

Posted by Patent Hawk at September 17, 2006 12:02 AM | Prosecution


As an examiner, I can tell you that is annoying to have to search for depending claims that add only limitations that are in the prior art. It's really a waste of time for all of us.

Posted by: M at September 17, 2006 8:36 AM

As far as asserting those dependent claims, it may be wise to assert it to make the asserted claim easier to understand for the jury and/or the judge.

As far as drafting, dependent claims whose limitations are anticipated by the prior art are often useful for claim differenation purposes (i.e. to define the scope of a term in the independent as broader than the term used in the dependent claim based on the theory that a proper dependent claim must narrow the scope of the independent and therefore the independent claim must be broader).

However, it is unclear to what extent, if any, the patent examiners really give to the doctrine of claim differenation during patent prosecution, especially given the proposed regulations that would ignore most of the dependent claims until the independent claims are determined to be patentable.

Posted by: Foo at September 18, 2006 11:51 AM

What about a scenario in which the independent claim is invalid for reasons other than anticipation/obviousness?

For example, perhaps the independent claim is found (in court) to be broader than the invention disclosed in the specification? In such a case, having a dependent claim that clearly is described/enabled would ensure that at least the more limited claim is valid, would it not?

Posted by: Nir at September 18, 2006 1:25 PM