License file organization when moving from one permissive license to another?

Question

I have a project that is currently licensed under the BSD 3-clause license, and I would prefer, going forward, to switch to the Apache 2.0 license. I plan on contacting the original contributors to see if they are willing to relicense their old code, but I am not counting on the majority of users doing so. However, this is not a major problem, since BSD and Apache 2.0 are compatible, so long as I retain the original copyright notice.

My question is, what's the best way to include the original copyright notice? Currently I have a single LICENSE file that includes the BSD 3-clause license. I'm planning on adding an AUTHORS file that will list all the contributors and which license their contributions are under (though this can also be inferred from the git history, if they haven't relicensed). The three obvious options are:

1. Two LICENSE files - LICENSE and LICENSE_OLD (or something like this)
2. A single LICENSE file containing both the Apache 2.0 and BSD license with a notice about which applies to which parts.
3. A LICENSE file containing the Apache 2.0 license, plus an included_licenses/ folder (or equivalent) that contains the BSD license (plus any other copyright notices necessary if I include code from other permissively licensed projects).

My preference would be #2, but my main worry there is that when you use standard boilerplate, it's easier for GitHub or other programs to automatically categorize your project, and I fear that combining two licenses may cause problems down the line. #3 is fine but it does add a bit of clutter to the repo.

Are any of these approaches more standard than others? Are there any known tricky legal issues with any of them?

Answer 1

If you really needed to change your license terms, I would say have your LICENSE file contain the Apache license. Make it a definite cut - this version is BSD - this version is Apache - the change is just a part of history. Present the project as an Apache licensed project, while the necessary files contain varying license info as needed.

If you look at the blender project, it is presented as a GPL project. You will also find 6 license files in the repo, while other licenses, such as zlib and BSD are also in effect for certain files throughout the repo. A few years ago a portion of it was re-licensed under the Apache license, but as a whole, it is still considered and promoted as a GPL project.

As for your file changes, alter the license header in the files you can and leave files you can't with the BSD license, then in the readme or the license section of your docs, state that the project is released under the Apache license and contains portions that are copyright xxx and available under the BSD license and that previous versions were released under a BSD license.

At the end, I would suggest that if it is just for your preference, don't bother changing the license. If you have a legal reason, then go and change the license on as many files as you can. You may want to consider splitting some of your files that are in dispute, foo/file_a.c is BSD code while foo/file_b.c is Apache code.