Umm, this is interesting..

[Shane Martin Coughlan]

Arnoud Engelfriet wrote:
> setuid wrote:
>> Well, first and foremost, he can't. Once the software is released under
>> the GPL, it cannot be revoked. He can TRY to claim that, but it won't
>> hold up under copyright law. 
> 
> I don't see why not. He cannot revoke the license he granted to
> people that are already using the work, but he can stop granting new
> licenses to new people.

I believe setuid and Arnoud were both referring to existing code
previously distributed when using the term 'revoke' above, and in that
context the GPL cannot be revoked.  The author is free to stop
distributing new copies of the code or change the terms under which new
copies are distributed, but that's another issue.

This story broke on Groklaw:
"One can't retroactively revoke licenses previously granted, unless the
license terms allow you to do so.  The most you can do is stop granting
new licenses."
http://www.groklaw.net/article.php?story=2006062204552163

> If I grant people licenses to walk on my land, I can revoke that license
> and put a big fence with barbed wire up. 

A public licence is a one-way grant from one party to many.  It has
cause and consideration.  Those receiving those rights rely on them and
the grant of those rights is irrevocable.  One cannot simply say "I have
changed my mind" and alter the terms of the code previously distributed.

I was chatting about this with a Free Software lawyer recently and he
suggested that under the "venire contra factum proprium" theory
(Germany, Italy) or the estoppel theory, this is impossible. He further
noted that putting software or other content under permissive licenses
is not an act of mere liberality.  It is more akin to a quid pro quo act.

Regards

Shane

-- 
Shane Coughlan
FTF Coordinator
Free Software Foundation Europe
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