Common Ground

Copyleft licenses all have one big thing in common: they remove particular common copyright law restrictions on copies of works. For most works protected by U.S. copyrights, the owner of a copyright uses the law to prohibit others from reproducing, adapting, or distributing copies of his work. But copyleft licenses grant some or all of those rights to every person who receives a copy of the work. It’s wrong to think of this as the copyright owner surrendering one or more of his exclusive rights. The copyright owner is simply offering a license to use the work in one of a certain number of ways. Subsequent uses of the work are then “licensed uses” so long as they comply with the terms of the license selected by the copyright owner. But if someone uses the work without complying with the license, then his use is an infringing one.¹

So, copyleft isn’t an absence of copyright. In fact, copyleft licenses rely on copyright law to enforce their provisions, which are usually intended to ensure that subsequent users of the work will always have the same rights to a work as did the generations before them.

The Incompatibilities

The problem here is that these licenses are not created equal.

One common family of licenses that is used for Web content is the Creative Commons series. These are designed to encourage creativity among Web users by making content available with only “some rights reserved.” But there isn’t just one license called “Creative Commons;” even in this single “family” of licenses there are a number of versions available. For example, a copyright owner could decide to require attribution on each copy made, or require that the work and derivatives only be used for non-commercial purposes. The copyright owner could even prohibit modification of the work entirely. One provision allows licensors to require that licensees “share-alike,” meaning that copies and derivatives of the licensed work must be licensed under identical terms.²

Compare the Creative Commons licenses to the GNU General Public License (GPL) or the GNU Free Documentation License (GFDL) and you’ll find that there are stark differences that often make it impossible to create “mixed” works that incorporate content licensed under different terms. Michael Scott, my co-host on the Podcast, learned this the hard way when he sought to use material from the EFF’s website (licensed under a Creative Commons license that requires attribution and that all uses be noncommercial) on his IT Law Wiki, a reference project that makes all material available under the GFDL (which does not require attribution and permits commercial uses). This kind of “mixed” work couldn’t be done without asking the copyright owner of the original work to waive certain rights so that the material can be relicensed under new terms.

Similar incompatibilities exist between the GPL and the Apple Public Source License (APSL), the Mozilla Public License (MPL), and the OpenSSL license. Does this mean that a distribution of GNU Linux (GPL) can’t be bundled with a copy of the Firefox Web browser (MPL)? Of course not. But it does mean that a developer couldn’t use code from the Linux kernel’s TCP/IP stack to improve OpenSSL and then distribute copies of that improved software under the OpenSSL license.

The Compatibilities

Luckily, not all of these licenses are at war with each other. For reference materials and documentation, one terrific new development is section 11 of the new GFDL version 1.3, which permits most existing material that was previously licensed under the GFDL to be relicensed under the Creative Commons 3.0 Attribution-ShareAlike license. This means that a work that was published under a GFDL license prior to the start of this month can be used in many Creative Commons projects. Wikipedia, the driving force behind this revision, is licensed under the GFDL, which means that all content that was posted to that site prior to November 1 is now more compatible.³

On the software side of things, the Free Software Foundation has also made things simpler by making the GPL–by far the most popular open source license–compatible with a variety of other copyleft licenses. With other popular licenses like the two-clause FreeBSD license on the list, you might be surprised by just how usable GPL code really is.

I’m an open source advocate because copyleft licenses enable people to create tools that can change the world,⁴ while providing future generations with code and text that can be used to solve absolutely any problem for which it is suited, including new problems that the original author did not foresee. But I also recognize that tangled and competing licenses don’t provide any benefit to anyone. In the future I hope to see an organization like the Free Software Foundation take more of a leadership role in this area, bringing the community together so that creative people can make the most of their work.

1. Jacobsen v. Katzer.
2. Hard-core copyleft advocates argue that only this version of the license is truly “copyleft.”
3. The November 1st date was a tactical decision designed to prevent people from gaming the system by adding materials to Wikipedia just to be able to use them under a Creative Commons license afterward.
4. No hyperbole here. Where would we be without Apache?

1. It’s important to understand that I’m not referring to software that is merely “free as in beer” meaning that it is given away without cost, but specifically software that is “open” in that its source code may be used, studied, and modified without restrictions.  Another term for this is “free, libre, and open-source software” or “FLOSS.”