Changing my own non-software project from GPLv3 to CC BY-SA

Question

I have a growing project which is a platform for 3D printers. The project contains printable parts and bills of materials. I defaulted to releasing it under GPLv3 without much thinking but since it's not software I'd rather have it under CC BY-SA.

When I release a new version of the platform some of the parts are modified to achieve new features.

Can I deploy a new version of my platform under CC BY-SA? previous versions will forever be under GPLv3 on GitHub. The tricky thing here is that the new CC version will contain parts from the previous versions and additionally the new, modified parts are based on the old GPL parts.

In my head the licence does not apply individually to each part as those are useless on their own - it's the whole platform that is versioned and licenced.

I have only accepted two commits, which fixed broken links in the documentation of the platform.

This all boils down to me doing something for the world, it's a passion project and I don't want it do be a legal nightmare.

Answer 1

You have accepted two other small commits to this project, but apart from those you are the sole rightsholder in your work. Moreover, although IANAL/IANYL, because the two commits simply correct the target text of some links in the documentation, it seems likely that they do not qualify for copyright protection.

As we discuss here, as the sole rightsholder you are not bound by your own licence terms. Just because you offered the work to people last week under the terms of GPLv3, you are not required to do so next week: you could offer it under different terms, or put it into the public domain, or refuse to convey it at all.

What you can't do is take away the rights granted under GPLv3 to those who received the code from you under those terms. But changing the licence to CC BY-SA going forwards seems completely fine to me.

Answer 2

As the accepted answer states, you should be fine doing this as you appear to be sole copyright holder. Were you not sole copyright holder, you would need either copyright assignment statements (this is actually one of the things that a lot of contributor license agreements include, but usually for different reasons) or explicit permission from each other copyright holder to change the license.

Your own reasoning is not quite correct, though. Each individual part of a project is under the license, whether or not it’s usable as-is without other parts, and any parts that are identical between the old (GPL licensed) version and the new (CC-BY-SA licensed) version are technically available under either license at the user’s discretion.

Font Awesome is an excellent example of how individual parts are separately licensed (albeit also a very good example of how not to run an open source project). They have three separate licenses, one for the icons (CC-BY 4.0), one for the fonts (SIL OFL 1.1), and a third for the ‘everything else’ (a standard OSI MIT license). None of these three parts are useful on their own, yet they still have separate licensing.

MySQL is probably the best example I can think of of something available under multiple licenses simultaneously. You can either pay Oracle for a special OEM-style license that lets you use it directly in your own proprietary projects, or you can use it under the GPL and deal with the implications of that (namely, that you can’t include it in a proprietary project without meeting the requirements of the GPL). The same principle applies when changing the license of a piece of code. As long as it remains unchanged it’s usable under either the old or new license at the user’s discretion.

Answer 3

Anyone who receives a future version will be able to use the rights granted by the GPLv3 or the rights under the CC BY-SA. A grant of GPLv3 rights is irrevocable. Here's what you agreed to:

A “covered work” means either the unmodified Program or a work based on the Program.

So all future versions of this software are covered works. That's what you agreed to when you placed those earlier versions under the GPL.

Each time you convey a covered work, the recipient automatically receives a license from the original licensors, to run, modify and propagate that work, subject to this License. You are not responsible for enforcing compliance by third parties with this License.

So you already agreed that every time you give someone a copy of a future version, they automatically receive a GPLv3 license from you.

All rights granted under this License are granted for the term of copyright on the Program, and are irrevocable provided the stated conditions are met.

And that lasts for as long as you hold copyright on the works you chose to place under the GPLv3.

You can grant CC BY-SA rights in addition if you want. But you can't prevent people from treating future versions as GPLv3 releases if they wish to do so.