Why So Many Obvious Dependent Claims?

Why do patents have so many dependent claims that add zero to a validity analysis? As an experienced patent prosecutor, I have an immediate answer: It is a complicated subject affected by a lot of things that are hard to explain. But now that you ask, let me meditate for a bit….

Oh!

A new answer: You are wrong. They add a lot to the validity analysis. Allow the professor to explain.

Claim 1: A widget having three or four claim elements described in a mix of functional and structural language.

Claim 2: A widget according to claim 1, made of plastic.

Claim 3: A widget according to claim 1, which is disposable.

The patent is litigated. Let me go out on a limb and assume that the main defenses are non-infringement and obviousness (the unfortunate defendant cannot find an anticipating reference). A pretty safe hypothetical right? It only covers 90+% of all cases.

Let’s briefly consider the plaintiff’s infringement case. Assuming we can show Claim 1 is infringed, is it going to be any harder to show infringement of Claims 2 and 3? No.

Now the validity attack.

To the jury: Claims 2 and 3 are clearly obvious, all widget in the marketplace are made of plastic and disposable.

Jury: Okay, that makes sense, Claims 2 and 3 are obvious.

To the jury: Reference 1 teaches a whole of stuff including some elements of Claim 1 and Reference 2 teaches a whole lot of other stuff including other elements of Claim 1, and a person with a PhD in the field and six years experience with the complicated requirements of making widgets would be likely to borrow just the right things from Reference 1 and Reference 2 to arrive at all the elements required by Claim 1.

Jury: Huh? You lost me. But clearly Claim 1 is not obvious in the same way that Claims 2 and 3 are obvious, is it? If obviousness is why Claims 2 and 3 are invalid, then Claim 1 is not obvious in the same way, and not invalid.