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I understand that, generally speaking, you may not issue a license on a copyrighted work if you do not own the copyright to that work. Licensing is an exclusive right of the copyright holder. Instead, you may prepare a derivative your other people's work, and license your own changes under some license. Recipients of your derivative may then exercise whatever freedoms over the combined work that are permitted by both licenses.

However, the MIT license includes the right to "sublicense" the work, which suggests I may be able to offer the MIT-licensed work to others under different licensing terms. Is this correct?

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The MIT-license is a permissive license which allows sublicensing under new conditions. This allows you to put MIT-licensed software into a proprietary product. You can even change MIT-licensed code and then redistribute it with a new restriction that it must not be redistributed!
(e.g. Unreal engine's license has such a restriction).

However, you can only add conditions, you can not remove any of the conditions the MIT license already places on it, which means however you sublicense it, you must retain the original MIT copyright notice.

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    Your restriction, however, doesn't do anything since they have an unrestricted license from the original author anyway. As the MIT license says, "Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction..." So you can offer it with a restricted license if that's more convenient for you, but you can't enforce the restrictions since they also have an unrestricted license from the original author. Nov 22, 2019 at 12:49
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    @DavidSchwartz However, the MIT license only applies to the original software you got under MIT from the original author. Any modifications you do to the software can be put under different conditions. So your customer who would like to distribute the software under MIT could extract the original MIT content and redistribute that, but not the stuff you added. That's how MIT is different from a "viral" license like the GPL which "infects" any sourcecode it gets combined with.
    – Philipp
    Nov 22, 2019 at 13:02
  • Absolutely. And you don't have to provide them any help in figuring out which parts they do or don't have an unrestricted license to. (At least, so long as your work really does transform the original work and you aren't abusing your copyright in one work to restrict the use and distribution of another. That could be considered copyright misuse. See, for example, Assessment Technologies of Wisconsin, LLC v WIREdata Inc.) Nov 22, 2019 at 13:05
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Probably not. While I have not been able to find any definitive reading of what the intent of the "sublicense" permission is, it appears to merely mean that you may pass the rights you receive on to others when you share the software.

I'm not a lawyer, and there may be a more airtight way to arrive at the same conclusion, but the possibility of changing the license appears to be naturally precluded by the license's requirement that

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

The license does not allow you to remove the text of the MIT license from MIT-licensed software, so it seems unlikely that you could sensibly change the terms of the license while unable to lexically remove the license from the software.

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  • I thought "this permission notice", online included the section you quote. Not the rest of the license text. (plus the copyright notice)? Apr 8, 2016 at 9:20

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