[LAD] GPL Violation Alert! - Sorry if this is a duplicate

[Chris Cannam]

On Tue, Aug 4, 2009 at 8:46 PM, Arnold Krille<arnold at arnoldarts.de> wrote:
> And I always wonder how Trolltech would enforce people to not use the GPL-
> version to start development and only buy a commercial license shortly before
> publishing ones own app for money. They actually can't because the sources of
> your app (should) not leave your home/business before that, so they wouldn't
> know...

It's a restriction of the license for the commercial edition -- you're
not permitted to use it at all with code you developed using the GPL
(or, now, LGPL) edition previously.  If you want to do that, you have
to buy back-dated licenses covering you all the way back to the start
of development.  You're right of course that they have no obvious way
to find out, except by auditing you -- I have no idea whether anyone
has ever actually been "caught" this way.

It's a very strange condition I think, and one with countless
ambiguities: can you reuse code you previously wrote for a completely
separate open source project but own copyright to? do you have to
audit everyone you employ to ensure not only that they own the
copyright for code they might incorporate, but also that it wasn't
written when they were using a GPL edition of Qt? what if it's code
that doesn't itself use Qt but was written as part of an application
that did? are you legally permitted to use code that someone else not
associated with your organisation wrote when using the GPL edition and
then re-licensed to you? what about code within Qt itself that was
written by someone using the GPL edition and then re-licensed to Qt?
etc, etc.

As far as I'm aware there are no reliable answers to questions like
these, but Nokia persist with the clause (at least I think they do --
it certainly lasted beyond the shift to LGPL) presumably because
there's no obvious better way to avoid the situation you describe.
Companies presumably pay up partly because they like risk even less
than they like expense.


Chris