The so called “copyleft” condition,[1] a provision included in one form or another since GPLv1, limits the ability of authors of works derived from GPL-licensed software to release their own work under licenses more restrictive than the GPL. In its current form, the provision requires authors of a modified version of software derived from GPL-licensed code to “license the entire work, as a whole, under this License to anyone who comes into possession of a copy. This License will therefore apply . . . to the whole of the work, and all its parts, regardless of how they are packaged.”[2]
In a license document that otherwise celebrates freedom and choice,[3] the copyleft condition at first seems out of place. It limits, rather than enhances, one potentially important freedom enjoyed by users of the software—the freedom to license derivative software works they create on terms of their choosing.[4] It is surely this loss of freedom that underlies pejorative labels, such as “viral” or “infectious,” that critics sometimes use in describing the GPL or other copyleft licenses.[5] As a programmer, using GPL-licensed code in your own work makes you a FOSS author whether you wish to be or not, because the copyleft condition “infects” your final
- ↑ See Richard M. Stallman, What is Copyleft?, in Free Software, Free Society, supra note 47, at 89.
- ↑ GPLv3, supra note 53, § 5(c). For earlier versions of the GPL’s “copyleft” condition, see GPLv1, supra note 17, § 2(b) (“You may modify your copy . . . and copy and distribute such modifications . . . , provided that you also . . . cause the whole of any work that you distribute or publish, that in whole or in part contains the Program or any part thereof, either with or without modifications, to be licensed at no charge to all third parties under the terms of this . . . License (except that you may choose to grant warranty protection to some or all third parties, at your option).”); GPLv2, supra note 52, § 2(b) (“You must cause any work that you distribute or publish, that in whole or in part contains or is derived from the Program or any part thereof, to be licensed as a whole at no charge to all third parties under the terms of this License.”). For a discussion of the interaction of the GPL’s copyleft condition with the license provisions requiring programmers to make source code available, see John Tsai, For Better or Worse: Introducing the GNU General Public License Version 3, 23 Berkeley Tech. L.J. 547, 564–68 (2008).
- ↑ See GPLv3, supra note 53, pmbl. (“The licenses for most software and other practical works are designed to take away your freedom to share and change the works. By contrast, the GNU General Public License is intended to guarantee your freedom to share and change all versions of a program—to make sure it remains free software for all its users.”).
- ↑ See James Grimmelmann, The Ethical Visions of Copyright Law, 77 Fordham L. Rev. 2005, 2028 (2009) (“the GPL makes you share source code because someone else shared it with you . . . free software licenses in general are incompatible with the default ethical vision of commercial exchange, and copyleft licenses go further by restraining downstream authors from taking part in the commercial exchange system as well”); cf. Dov Greenbaum, Academia to Industry Technology Transfer: An Alternative to the Bayh-Dole System for Both Developed and Developing Nations, 19 Fordham Intell. Prop. Media & Ent. L.J. 311, 404 (2009) (recognizing “legitimate concerns that viral or infectious terms in an exclusive license may serve as a disincentive to license”).
- ↑ See, e.g., Dennis M. Kennedy, A Primer on Open Source Licensing Legal Issues: Copyright, Copyleft and Copyfuture, 20 St. Louis U. Pub. L. Rev. 345, 362–63 (2001); Ron Phillips, Deadly Combinations: A Framework for Analyzing the GPL’s Viral Effect, 25 J. Marshall J. Computer & Info. L. 487 (2008); Greg R. Vetter, “Infectious” Open Source Software: Spreading Incentives or Promoting Resistance?, 36 Rutgers L.J. 53 (2004); cf. Kumar, supra note 50, at 9 (criticizing labels like “viral” and “infectious” as resting on a misunderstanding of the GPL).
