It Is Not Necessary To Cover Prior Art Embodiments

Although it is nice to write patent claims that cover all possible embodiments of an inventive subject matter, doing so is not necessary. It suffices that the claims are broad enough to provide a sufficient edge to beat out competitors in the marketplace. For example, assume that a client invents a face recognizer for use on highway patrol cars. Whereas the prior art developed systems that can only read faces on cars moving in the same lane as the patrol car, or on parked cars in adjacent lanes, the new device can read faces on moving vehicles in the same lane and in adjacent lanes. The applicant would like to claims systems that can read faces in the same or different lanes, but such a claim would not be allowable because of the prior art. It is enough that his patent claims systems that read faces in moving cars in other lanes. Given a choice of the prior art system or the new systems, police departments will inevitably choose the latter.

In short, the applicant didn't need to claim prior art functionality. All he had to do was claim the new functionality. He can still beat the competitors in the marketplace because their devices would be limited to the old functionality, which his devices could employ both new and old functionality. The purpose of a patent claim is not to claim the applicant's product, but to keep competitors out of the applicant's market space.

Now, should the applicant also include a dependent claim to additionally read faces in the same lane? Yes, absolutely. That way, a competitor would infringe the independent claim for a system that read faces in only adjacent lanes, and he would infringe both independent and dependent claims for a system that read faces in both adjacent and same lanes.