When this whole topic flared up I was immediately consumed, as you were, by many people’s misperception and understanding of the GPL. Now, I might have a number of my own misconceptions I suppose, but I would like to think that over the years, endless consultations with lawyers on the subject and being the architect behind Movable Type and Melody’s open source strategy, that I have amassed a certain amount of my own [layman's] expertise.

First, the GPL governs distribution, thus it is really only invoked when code is bundled and distributed together in a way that forms a derivative work. In other words, a theme by itself is a completely separate, albeit worthless, piece of code from WordPress. In that form, it shares absolutely no code with WordPress. As such, themes are distributed independently from WordPress itself, or IOW users must first download the theme, and then install it into WordPress in order for it to function.

We good so far? Excellent.

Now, let’s establish a fact: the GPL specifically states that I am permitted to make modifications to any GPL software in my possession, and that I am even permitted NOT to make my changes public, provided that I do not re-distribute my changes. As long as my changes are private and mine alone, I can do whatever I want. This to me is one of the most liberating parts of the GPL.

Still with me?

So the question in my mind turns to this: if I were to install a theme into my private install, have I created a derivative work just by doing so? Perhaps, but the GPL is only enacted when I choose to redistribute this “derived work.” Let’s look at two scenarios:

a) I want to create a version of WordPress that includes my own themes I have created. I (of course) am permitted to do this under the GPL, although trademark law would prevent me from calling it “WordPress.” Now, because my themes are distributed with WordPress, and because those themes when loaded by WordPress share the same memory space (a.k.a. dynamic linking), I have created a derivative work of WordPress. As such, in order to be in compliance with the GPL the themes I have choosen to redistribute alongside WordPress must also be GPL (or GPL compatible), even if those themes adhere to an API that keeps the code physically separate.

b) In this next scenario, I make modifications to a GPL theme directly. I am under no obligation to share my modifications unless I choose to redistribute those changes to anyone. So even though I have created a derived work by making modifications directly to the theme, the GPL only comes into affect vis-a-vis my changes when I redistribute them.

The point to underscore is the the GPL is only relevant and can only “infect” code when code is distributed. Now the GPLv3 attempts to provide greater clarity around what “redistribtion” means and attempts to define the process of making something available through a web site (e.g. a blog) as “distribution.” This is very controversial and one of the reasons I suspect that WordPress is still only licensed under GPLv2 where this definition of distribution is more ambiguous. If they adopted v3 of the GPL, then all of the proprietary code written by Automattic powering WordPress.com would also need to be made available under the GPL. Not something they are likely to want do IMHO.

Back to the core issue and question: “if I were to install a theme into my private install, have I created a derivative work just by doing so?”

I maintain that no, you have not. At least not as it relates to the GPL. The GPL gives me permission to install and modify my GPL software however I want without obligation of any kind. That includes installing themes and plugins.

Let’s look at it this way:

Pretend I am a large media company and I have just paid a design firm a handsome sum of money to design for me a web site powered by WordPress. I install the theme they gave me, and in so doing create a “derived work.” According to SFLC and the arguments currently being made, this company would now be compelled by the GPL to open source their code/theme. Implying that every theme ever made for WordPress must be GPL. This is utter nonesense. Seriously, is there anyone who believes this could possibly be true? It can’t be because no code is actually being distributed. It is being commissioned and is owned privately by someone. This it is shielded from the GPL.

No, Byrne, you misunderstand, code commissioned and paid for privately is ok. What about the themes being sold through a store front?! Ok, sure, in this scenario code is being distributed. But the code being distributed is not a derived work in and of itself. It is only a derived work after it is installed and executed. My code would only be governed by the GPL if I redistributed WordPress with my theme pre-installed.

This was a long comment. My apologies. But despite all that people have written on the GPL, and especially on this topic, it is still amazing to me how few people understand what the GPL actually governs.

Thank you for your great series. I look forward to the next piece.