Can a recipients rights under GNU GPL be revoked?

[Ben Finney <bignose@debian.org>]

Howdy all,

Recently in this forum, some concerns have been raised about works
covered by GNU GPL. In particular, whether a recipient of a work,
received under conditions of the GNU GPL, can have the freedoms of the
GNU GPL later withdrawn in that same work.

To reassure those who might worry whether they can reply on the freedom
granted in a work, it is worth reading the GNU FAQ document for the GNU
GPL at the Free Software Foundation:

    [For any GNU GPL-licensed work,] the public already has the right to
    use the program under the GPL, and this right cannot be withdrawn.

    <URL:https://www.gnu.org/licenses/gpl-faq.en.html#CanDeveloperThirdParty>

The same answer is in the FAQ specifically for the GNU GPL version 2.0
<URL:https://www.gnu.org/licenses/old-licenses/gpl-2.0-faq.html#CanDeveloperThirdParty>.

You can read more in the Software Freedom Conservancy's document
_Copyleft and the GNU General Public License: A Comprehensive Tutorial
and Guide_, specifically in §7.4 “GPLv2 Irrevocability”. That concludes:

    Whether as a matter of a straightforward contractual obligation, or
    as a matter of promissory estoppel, a contributor’s attempt to
    revoke a copyright license grant and then enforce their copyright
    against a user is highly unlikely to succeed.

    <URL:https://copyleft.org/guide/comprehensive-gpl-guidech8.html#x11-540007.4>

In other words: Any copyright holder can *say* they wish to
retroactively revoke the GNU GPL to some party. However, unless that
party has violated the conditions of the GNU GPL grant they originally
received, there does not appear to be any enforcible threat of
revocation that would succeed.

I hope these, along with the many court cases world-wide that have
tested the GNU GPL and found it to be enforcible, can reassure those
considering whether a particular copyright holder's whim can revoke the
freedoms guaranteed in a GNU GPL-covered work. I'd say there's nothing
to worry about from those threats.

-- 
 \       “I distrust those people who know so well what God wants them |
  `\    to do to their fellows, because it always coincides with their |
_o__)                      own desires.” —Susan Brownell Anthony, 1896 |
Ben Finney