If a project is released under GPLv3+ and GPLv4 is less restrictive what happens?

Question

I've seen in multiple places project owners choosing to stick with GPLv2 to prevent the FSF from releasing a license that the project owners don't agree with but I've never seen reasoning beyond the claim that the next GPLv4 could be disagreeable. Are there any real licensing dangers associated with this ability to seemingly change your project's license at will?

For example, if the FSF were to release "GPLv4" and it's just the exact text of the MIT license what would happen to projects that are licensed under GPLv3+? Could they be licensed under the terms of "GPLv4"? Are there restrictions within the GPLv3 that prevent this from happening?

Answer 1

For example, if the FSF were to release "GPLv4" and it's just the exact text of the MIT license what would happen to projects that are licensed under GPLv3+? Could they be licensed under the terms of "GPLv4"? Are there restrictions within the GPLv3 that prevent this from happening?

Yes, that is precisely the idea. See The FAQ about GPL:

From time to time, at intervals of years, we change the GPL—sometimes to clarify it, sometimes to permit certain kinds of use not previously permitted, and sometimes to tighten up a requirement.

Those projects could then be used and distributed under the terms of either GPLv3 or GPLv4. The original author of the projects has at some point chosen this by going with the "or any later version" option and there is of course no possibility for the GPLv3 license to somehow prevent the author from doing this.

If you don't think that you will automatically agree with FSF on what is actually an improvement to the license that you chose today it seems a bit risky to go with the "or any later version" option.

Answer 2

Section 14 of GPLv3 says:

The Free Software Foundation may publish revised and/or new versions of the GNU General Public License from time to time. Such new versions will be similar in spirit to the present version, but may differ in detail to address new problems or concerns.

Therefore I would argue that a GPLv4 can't be a MIT-like license. Further I would say that "similar in spirit" means that every new version needs to be again a strong copyleft license which only "differ in detail to address new problems or concerns". That's also what we saw with GPLv3, it does the same as GPLv2 adjusted to the technical and legal changes to make sure that the GPL will continue to be a strong copyleft license.

I would highly recommend to keep the "or any later" part or chose one of the other options described in section 14 like for example a proxy. This is crucial for long-term maintainability of the legal side of a project.

Answer 3

Your concern is a legitimate one. When you are licensing a software under GPL v2 or later, or under GPL v3 or later, you are basically trusting the FSF for the future licensing of your software. They can very well use this for very specific purposes and it happened in the past: the GFDL license was updated to allow Wikipedia to switch licenses from GFDL to Creative Commons (cf. https://www.gnu.org/licenses/fdl-1.3-faq.html).

Similarly, when licensing a software under MPL 2.0, the license contains a provision relative to later versions (this provision does not really let the choice to the licensor, whereas the GPL does):

You may distribute the Covered Software under the terms of the version of the License under which You originally received the Covered Software, or under the terms of any subsequent version published by the license steward.

The conclusion is that when choosing to distribute your software under a license of the FSF with the clause "or any later version", or when choosing to distribute your software under MPL 2.0, you have to trust the foundation which authored the license (FSF in one case, Mozilla foundation in the other).