Enforceability of Open Source Licenses
This article raises some of the issues related to enforcement of open source licenses.
Closely related to the issue of whether an open source license is merely a copyright license or a contract is the question of whether (or to what degree) a court will enforce an open source license. Both licensors and licensees of open source may wish to enforce specific terms and conditions contained in the license. In addition, a contributor to open source might want to enforce his or her own copyrights embodied in the open source work, as may a third party whose intellectual property was added to the open source without authorization. On the other hand, a licensee unhappy with some of the license restrictions might try to claim that a valid contract was never formed, which could enable the licensee to use the open source without restrictions. But because no open source license has yet been tested in a U.S. court, the outcome of any claims by licensors, licensees, contributors, and third parties is not clear.
A court might view open source licenses through the lens of contract law if it rejects the argument that a copyright license may be governed only by copyright law. Contract law generally but not always requires a clear indication of mutual assent to the license terms. If an open source license is simply embedded within the software itself, without any other notice to a prospective licensee, then there is some question as to whether the license can be enforced as a contract; the user would not have received explicit notice of license terms or the opportunity to explicitly agree to those terms. The BSD, GPL, and LGPL are examples of licenses that may run up against this issue, as they do not have specific requirements about notifying prospective licensees beyond including a copy of the license within the source code itself. The MPL seeks to avoid the problem of questionable contract formation by requiring that licensees include a copy of the MPL in each file of source code or other location where a user would be likely to look for it, including documentation. The MPL also requires that a copy of the license be "conspicuously included" in any executable program containing MPL-licensed source.
If a court does not uphold an open source license as a contract, a user of the open source software is still subject to copyright law. Without the copyright holder's express authorizations in the license to copy, modify, and distribute the source code, a user of the open source may be subject to copyright infringement claims. A court could find, however, that the owner's act of making the software available with no clear indication that there was an associated license agreement gives rise to an "implied license," thus allowing continued use by the licensee. Alternatively, a court could find that a licensee's use of the open source was protected as "fair use."
- Rosen, Lawrence (2005), Open Source Licensing: Software Freedom and Intellectual Property Law, Prentice Hall, Ch. 12. Available at http://www.rosenlaw.com/Rosen_Ch12.pdf. Rosen’s section on “Enforcing the Terms of a Contract,” pp. 280-283, is especially helpful for non-lawyers.
- St. Laurent, Andrew M. (2004), Understanding Open Source and Free Software Licensing, O’Reilly, pp. 147-154.