The Chain of Title for Patents

Once again, a patent is a right to exclude others from making, using, selling or offering to sell, or importing a specific claimed invention. An inventor writes his claim in precise terms in a patent application and then a patent examiner reviews the claim for patentability. Only claims that meet a legal standard will be approved. The legal standard for patentability involves arcane criteria of novelty and unobviousness for which a qualified attorney is often indispensable . Upon approval of the patent application, the inventor (or his assignee) receives a limited monopoly right to prevent unauthorized practice of his patent.

A patent differs from a copyright in a fundamental way: A copyright prevents a third party from copying or modifying the original work, but a patent restricts everyone who uses the patented invention whether the invention has been copied or not. Even someone who independently creates the same invention and doesn't copy the first inventor still cannot make, use, sell or offer for sale, or import the patented invention because he's not the first inventor. It makes no difference whether the second inventor even knew of the first invention.

As with any other form of intellectual personal property, patent rights can be sold or given away, inherited, lost in bankruptcy, or licensed. In that sense, there can be a chain of title for a patent just like there is for a piece of real property. It is often possible to trace that chain of title using public documents on file with the government patent office.

Unlike copyright rights to collective and derivative works that are subject to the prior licenses for each of the contributions and modifications that preceded them, a patent has only one current owner we must worry about. (There may actually be multiple inventors or owners of a patent, or different owners of the exclusive rights in a patent. For our purposes, we can treat those multiple owners as one person.) There is no concept of a collective or derivative work in patent law. One either infringes a patent or one doesn't.

Before you can implement a patent claim in software, you need to determine who actually owns the relevant patent rights and whether you have a license to practice it. The patent owner may be the original author of the copyrighted work from which you're creating a collective or derivative work, but it may also be someone entirely different, perhaps someone neither you nor the copyright owner ever heard of before.

It is a complex and enormously expensive task to find all relevant patent claims and analyze them to determine whether you have the right to make, use, sell or offer for sale, or import your software. It is no wonder that most software authors ” open source ones and proprietary ones ”don't devote the time or money needed to undertake that search and analysis. They often merely wait to be surprised by bad news. If a patent claim by a third party is asserted against your software, you can simply stop using the patented invention, or challenge its validity in the patent office or in court . Another obvious choice is to seek a license to the patent.

A patent license can be narrow or broad, specific to a particular implementation, or broad enough to cover any possible implementation of the patent. Depending upon the specific terms of the patent license, it may not include the right to implement the patent in a collective or derivative work. There is no free software or open source definition for a patent license, and so each license must be analyzed to determine whether its terms are compatible with such software.

At least in theory, you must obtain a license from any patent owner whose patents are practiced in any software you make, use, sell or offer for sale, or import. In practice, hardly anyone bothers until it is too late. As I discuss various open source licenses later in this book, I will explain how each license handles ”or doesn't handle ”this potential patent problem.