Every couple of years, there arises a dispute over what the GPL does and does not require.

Three years ago, it was Joomla burning its bridges with SMF.

This month, it seems to be a debate between Wordpress and its theme authors.

Both revolved around a dispute over the meaning of the term "Derivative Work," as listed in section 0 of the GPLv2: This License applies to any program ... The "Program", below, refers to any such program or work, and a "work based on the Program" means either the Program or any derivative work under copyright law:

When trying to put together an informed opinion, you find copyright law doesn't seem to fit the situation. In example after example, derivative works are said to include a significant portion of the original within them.

Hold the Bus

I thought the legal scholars at the FSF and the SFLC said that a file which makes even a single call to a GPL-licensed function in PHP means that the calling file becomes a derivative work. How does that sync with the idea of including a significant portion of the original? Well, it doesn't.

What Is Software?

For the above paragraph to be true, you have to agree that software is wholly defined by the source code which makes it tick. From the point of view of a bridge or theme author, I'm really not using any significant portion of the software. I'm copying 20 lines from the core to bootstrap the environment or I'm making a call to output a list of some data. If I'm using less than 1% of the code which is covered by the GPL in this theoretical non-GPL project, surely they can't claim that this is a derivative work, right?

Well, this is (from my point of view) the unsolved mystery. If the courts decide that the source code is the end-all-be-all, then suddenly this derivative work business is over. If we look at a certain ratio of included source to total source (in the original work) as fair use, and not bound by the terms of the GPL, then any contributor who wants to use the WTFPL or the Apple iTunes license, they would be free to do so.

But I was once told that software and hardware were inseparable. So let's say that the court looks at this from a non-engineering point of view, and feels that more than the source code itself needs to be considered. The litmus test might be whether or not the supposed "derivative work" has any value without the original work. Themes and bridges would definitely fail this test, as would any software designed to work with some other software. The courts could also decide that the complete state of the finite state machine (computer) which the software is running on should be considered. This seems to be what the SFLC is banking on, based on their response to WordPress.

These legal opinions seem to be floating around without any case law to back them up, so the definitions remain very much up for debate. As far as I've been able to find, there have been no cases involving the definition of "derivative work" in software which have been ruled on by a judge and/or jury in the United States or elsewhere. '1

The bombshell

Marco Tabini wrote about this issue on his blog earlier today. He mentioned that all this analysis is silly. I think he's mostly right. If WordPress Foundation, Open Source Matters (responsible for Joomla!), or any other vendor of GPL-licensed software really wants to resolve these issues with finality, file suit.

It might be a disaster for your product and your community, but it would aid the FOSS universe. Settling the "derivative work" question (even if only binding in the United States) would bring considerable value to the projects who would still be standing.

'1 http://perpetualbeta.com/release/2009/11/why-the-gpl-does-not-apply-to-premium-wordpress-themes/ does cite "Galoob v. Nintendo, 1992". However, here, the court's opinion seems to revolve around how the Galoob product does not permanently incorporates a Nintendo game and is therefore not a derivative work. The question of software derivation in the face of an open-source climate is not addressed to my satisfaction. Also, if the DMCA existed in 1992, Galoob would clearly have been found liable under that statute.