Why I Stopped Using the GPL
March 30, 2020
Some time ago, I wrote an article about why I used the GNU General Public License for my software despite the arguments that it can't possibly be a free license when it employs restrictions on how the software may be distributed. Since then (and it's been some years now), I've significantly changed my mind about the GPL and copyleft in general.
Once upon a time on IRC, I got into an argument with my friend apotheon about copyleft. apotheon is the founder of the copyfree initiative. For a long while, I had thought that copyfree was just a pretentious name for so-called "permissive" software licenses which permitted proprietary software developers to appropriate free software to enhance their user-subjugating programs, a pretense to virtue over superior copyleft licenses. However, he presented to me an argument I'd never heard before: copyleft is self-defeating in practice.
Take for instance the classic case of Linux and ZFS. Linux is an operating system kernel licensed under the GPL version 2. ZFS is a file system licensed under the Common Development and Distribution License (CDDL) of some version. Each of these are copyleft licenses, i.e. when you "distribute" any other software with them in particular ways, even if that other software is released under a different license, the collection as a whole must be distributed as if everything was under the copyleft license. That being the case, it is illegal to distribute GPL and CDDL software together as one integrated software system, because each effectively requires some parts of software distributed under the terms of the other license to be relicensed. Unfortunately, in the case of Linux and ZFS, the specifics of what distribution conditions trigger these restrictions are a subject of some debate, and until someone gets fined or goes to jail after a court judgement, we simply don't know for sure where the line lies.
Some copyleft licenses have explicit compatibility with other copyleft licenses. For instance, the Creative Commons Attribution-ShareAlike (CC-BY-SA) license is explicitly compatible with the GPL of some versions. This was a conscious acknowledgment by the Creative Commons license authors that their license would get in the way of their very goal if people wanted to use a different license for their software (the CC licenses are generally aimed at artistic works rather than software). However, the same cannot be said for the CDDL or many other copyleft licenses. They covered one flaw but far from the entire issue, and the GPL doesn't have any explicit compatibility clauses; it relies on other licenses being compatible with it explicitly.
Perhaps copyleft terms do discourage some proprietary software developers from using free software as a base for nonfree software, but many companies simply ignore the terms with the knowledge that the developers lack the funding to take them to court for copyright infringement. Why bother with a facade of security whilst stepping on the toes of those who want to make more free software?
Copyfree licenses also don't truly depend on copyright law to work. They practically simulate how things would be if the government simply didn't intervene, which is really how I wanted it to be anyway, even though I acknowledged copyleft wouldn't work in such a system. About the only thing modern copyright law does that I appreciate is that it provides a means of taking someone to court for plagiarism, but it doesn't even really do a good job of that. We'd be much better off without copyright and perhaps with a specific anti-plagiarism law.
It became clear to me that my license preferences were at odds with my real goals and principles. I was trying to justify means with ends that would not even be reached by those means, and so I stopped using the GPL.
For those curious, my preferred license now is the Copyfree Open Innovation License (COIL). I use either it or the GNU All-Permissive License depending on the scope of the project and whether I am concerned about software patent issues.