Lawyers and programmers have at least one thing in common: their day-to-day work puts them in contact with issues that seem obscure and esoteric to the general public. That makes the terms of open source licenses doubly difficult to understand, but Lawrence Rosen does an admirable job explaining them in his book.
If the open source movement were a person, he'd not only be old enough to drink, his mother might be wondering why he wasn't at least dating seriously yet. It was born in 1989, with Richard Stallman's release of his GNU project software under the first version of the GNU GPL. Bill Joy released a free version of UNIX under the University of California's Berkeley Software Distribution (BSD) license. Not surprisingly, these two licenses are among the first ones discussed by Rosen, but before we can get that far, there are certain concepts we need to understand. Rosen builds the foundation we need in the first four chapters of the book.
You see, as Rosen explains, "This book is about the law but it is not written for lawyers." It is written for programmers, and it's apparent that Rosen hopes to provide some clarity for those who are thinking of contributing to or even starting their own open source software projects. These are important decisions with legal consequences, and any programmer who doesn't understand the legal concepts before contributing to or starting such a project may be courting disaster.
The first, fairly short chapter focuses on definitions. In particular, it explains what is meant by "software freedom" and how it is different from other legal concepts, as when an item is said to be "free of defects." It also explains the necessity of coining the term "open source," and gives the ten-point Open Source Definition from the OSI. He then simplifies things for his readers by explaining five open source principles that are consistent both with the OSI's definition and the Free Software Foundation's principles. He refers to these five key principles throughout the book.
In the next chapter we enter the legal world. Specifically, Rosen discusses the principles and key concepts surrounding intellectual property. He uses the metaphor of left brain and right brain to help explain the difference between what can be copyrighted and what can be patented, and why software can be said to have elements of both. This of course leads to a discussion of the rights of copyright holders and patent owners, collective and derivative works, the chain of title for patents, and so forth. Rosen's writing style makes it much more engaging than it sounds.
The third chapter is devoted to distribution of software and the unique issues that open source software faces in this regard. "What is unique about the open source process is that once software has been licensed under an open source license, the collaborative process is no longer tied to a single individual or company." Rosen explains the implications of this difference, and also has some reassuring words for those of us who merely use open source software rather than create or distribute it ("All open source software, whether licensed under academic or reciprocal licenses, can be freely used by anyone, anywhere, for any purpose whatsoever.").
The fourth chapter provides the legal meaning of "license," as well as related terms. Here we delve into contract law and touch on warranties as well as issues of offer, acceptance, and consideration. Now we're ready for the rest of the book.