"More than 20 years after medical expert systems were first developed, the USPTO issued two patents simply on the concept of using a computer to help physicians choose medical treatments. A company that purchased these patents claims that "the diagnosis and treatment of most chronic diseases will fall under the claims of these patents." Already it has filed patent infringement suits against seven companies in three years and it threatened to sue a university for hosting a freely available HIV database. Perhaps most startling of all, that same university — where much of the seminal research on expert systems took place — entered into a licensing agreement intended to limit the use of the HIV database, which had been created by one of its own faculty."
Source: http://www.harmfulpatents.org/