Can I take MIT licensed code and distribute it under BSD?

Question

There is django-auth-kerberos (MIT) which I want to cherry-pick as initial implementation and include+modify as a plugin to python-social-auth/social-core (BSD). Does the MIT license permit this? Are there examples from other projects that did this?

Backstory:

I want to re-use the original kerberos implementation and tests, retaining all copyright attributions, commit authorship info, etc and subsequently modify them to work in the context of Python Social Auth because this is what we use and don't want to add yet another auth library.

I plan on sending a PR to PSA where the first commit will be the original kerberos implementation so the history is visible and the 2nd commit will be modifications to match the new framework.

Answer 1

Yes, you can license your modified version of an MIT-licensed software under any variant of the BSD license.

However, you must still comply with the MIT license. This means that you must keep the original copyright notice and license intact. In that case the MIT license notice is merely informational and does not affect the licensing of your code. In such cases, it may be helpful to show your license, and the original directly under it:

Copyright 2018 Your Name

Redistribution and use in source and binary forms ... BSD license

Based on SomeOriginalSoftware (https://example.com/)

Copyright 2014–2017 Original Copyright Holder

Permission is hereby granted, ... MIT license

Some projects use their project-wide LICENSE file to track extra license notices or differently-licensed components. For example, Python's license still includes licenses for older Python versions. Pandoc's license is absolutely exemplary and tracks licensing and copyright status for individual files and folders, similar to the machine readable copyright files that most Debian packages have. The Apache 2.0 license even anticipates extra legal notices, which should be collected in a NOTICE file.