Exceptions to Intellectual Property Protection

Not everything in software is subject to copyright or patent protection. It is possible to write software that is not protected by either. For our present purposes, these are the two most important exceptions:

1. You cannot use copyright law to prevent someone from practicing the underlying ideas in the software. Copyright protects only expression. If there is only one way to implement an idea in software, anyone can copy the software unless it is also protected by patent (or by a trade secrecy restriction, something that never applies to open source software whose source code is published).

2. Before you can use patent law to prevent someone from practicing the underlying ideas in the software, you must actually apply for and obtain a valid patent. That can be both expensive and difficult. The validity of a patent can be challenged in court . If the author of the software doesn't have a patent, anyone can build equivalent software from scratch without asking the original author's permission.

These exceptions to copyright and patent, and a few others, often become important in intellectual property litigation. Authors of software always claim that they own intellectual property in the form of copyrights and patents, but at the end of the day, they may still have to prove in court that their software isn't one of those unprotected exceptions. I'll describe how that plays out in court when I discuss open source litigation in Chapter 12.