Can a user redistribute pay-only GPL derivative? and more...

[Joseph Heenan]

Ethan Piliavin wrote:

> 1)      Am I correct in understanding that: Under GPL, one can release a 
> derivative work of another GPL’d project, as long as it is also under 
> GPL, and the second party can even charge for the derivative work (and 
> only send sources and/or binary after payment).

Yes, correct.

Note that if there is a separate charge for source code, is must be 
supplied "for a charge no more than your cost of physically performing 
source distribution, a complete machine-readable copy of the 
corresponding source code".

> 2)       If the above statement is true, can a third party now use the 
> source code provided by the second party (that charges) and create a new 
> (double derived!?) program and sell or give it away (under GPL)?

Yes.

Note however that is the second party is actually claiming that the 
source code/combined work is NOT under the GPL, you have no right to 
sell or give away any derived work. In that case, the second party is in 
breach of copyright, and could be sued for damages etc by the copyright 
holder.

If you were to take the second party work and distribute it (or a 
derived work) in this case, you would be in breach of their copyright, 
as well as them being in breach of the original copyright. This is a 
tricky issue, and you would want to consult with both the original 
copyright holder(s) and a lawyer.

> Is there any obligation from the third to the second party once the 
> transaction is complete (other than GPL)?

Assuming the second party is distributing their source/binary under the 
GPL, no.

> 3)      Would there be any legal implications / gpl problems / copyright 
> violations in a case where a user redistributes a GPL’d program+code 
> that the original author charges for?

There are none, provided the original author is not trying to claim the 
work is not GPL.

> 4)      Is there any difference for interpreted script programs (ala 
> PHP) where the source essentially is the program?

Yes, slightly. It is possible that the source code supplied by the 
second party is obfuscated. To distribute that work under the GPL, they 
would be required to provide a non-obfuscated source on request, 
possibly for the payment of a small fee.

Dislaimer: I am not a lawyer. This is not legal advice. The situation 
may differ in your country.

Joseph