Prentice Hall, 2004

ISBN: 0-13-148787-6

$39.99 US

Software licenses are like pluggable authentication modules—bad to try to re-implement yourself but important to get right if you want to be secure. Technology attorney Lawrence Rosen offers a manageable introduction to the subject in this book. If you ever have trouble getting the right to use free software at work because of license concerns, buy a copy of this book. If your company is planning to release free software, Open Source Licensing gives you the background to get the most out of your meetings with a lawyer about the license.

This book is a useful field guide to the rights and obligations that the common free software licenses offer and their strengths and weaknesses. It also covers the essentials of copyright and patent law as they apply to software. Rosen also introduces his new licenses, the Open Software License and Academic Free License, which he says fix yet-unexploited legal bugs in older licenses.

For someone who was motivated to write his own set of software licenses, Rosen is generous to the industry-standard GNU General Public License (GPL). He gives the GPL a clean legal bill of health, which makes this book helpful when deciding to use and contribute to GPL-covered software. But he does offer a clear explanation of why a software author would want the additional teeth that his new licenses offer. By binding users to a contract, he lets the licensor set the venue for any lawsuit over the license, insist on attorney's fees and obtain other advantages in court.

This book does an especially good job of covering how the common open-source licenses handle software patent threats and the differences in the patent defense measures in each license. However, it would have been helpful to include a discussion of one approach that patent holders have taken when contributing patented methods to GPL software—offering a patent license separate from the GPL but ostensibly compatible with it. Linux contributions from IBM, Red Hat and FSMLabs are licensed this way, under three different patent grants.

Although the book is strong on the legal side, it's weak on what many consider the overwhelming network effects of the GPL and the advantages of keeping new projects compatible with the existing universe of GPL code. It's surprising that a 2004 book that covers both the Mozilla Public License and the issue of relicensing doesn't mention that Mozilla began relicensing to include the GPL in 2001.

The business decisions about what software license to adopt are yours, and this book's power to dispel Fear, Uncertainty and Doubt about licenses and bring FUD victims into the software commons is invaluable. Reading Open Source Licensing is an ideal first step in the license decision process.