How to Invent and Protect Your Invention: A Guide to Patents for Scientists and Engineers

7.3 INFRINGEMENT SUITS

So what happens when a patent holder learns that someone is infringing her patent? To protect her rights, the patent holder must initiate an infringement suit. An accused infringer will typically try to defeat an infringement suit in two ways: (a) The accused infringer tries to invalidate the obstructing patent claim, and (b) he attempts to show absence of infringement. In order to invalidate a claim, the infringer will exhaustively reexamine every last shred of prior art and will leave no stone unturned, often by the use of expert witnesses, to find references that anticipate the claim (i.e., to destroy novelty) and to find prior art that teaches the subject matter (i.e., to destroy unobviousness). And the chances for finding relevant prior art that read on the obstructing claim are not bad considering that patent examiners have only limited time and resources to ferret out every last thing that may read on the novelty and unobviousness of an invention.

Secondly, the alleged infringer will try to show that his actions were outside of the scope of the claims—that is, that he was not infringing the claims at all. He can do this by stressing differences between his product or process and the product or process described in the patent. This is where claims interpretation really comes into play, and broad open claims prove more valuable to patent holders than do narrow closed claims (see above).