The Electronic Frontier Foundation [EFF.ORG] has a “patent busting” activity that watches for patents that “should never have been granted” (my language) and works to invalidate them, or at least invalidate as many of their claims as possible. You’d be amazed at the kinds of things that have been patented that were just plain obvious, or had clearly been invented years before by someone else. I’m particularly sensitive to this because of my long history in computer-based learning and education. As an example, EFF is focusing on busting a patent on online test-taking. This one hinges on a method for charging for the tests and splitting the revenue, but nevertheless it seems absurd that someone could obtain a patent on splitting revenues from test-taking, doesn’t it?
 A patent hinges on any number of “claims” which are generally separate and somewhat independent of each other, and these are usually structured in such a way that they’re like ”gotchas” — if the patent owner can’t get you on one of them he may get you on another of them. There is a tension between how much is claimed by the inventor and what claims the patent office allows — and this back-and-forth starts at the time a patent application is filed, continuing until the patent is either issued, claims are removed, or the application is denied. On a granted patent, its strength is generally related to how many claims there are and how broadly they can be applied to a competing invention. Attacking a patent involves showing that individual claims should be invalidated, until you have either stricken the entire patent or reduced it to a few claims that are so weak it can no longer be effectively used.