There are an abundance of sources commenting on the GPL/WordPress/Thesis flap, so search them out if you want the details (Spoiler: Thesis is spectacularly in the wrong.)
Most of the reading at this point walks well-trod ground, but one bit of commentary by The Accidental Businessman (Marco Tabini) deserves special attention:
You could say that Matt’s opinion counts, because he wrote the software and he should have the right to decide how his software is distributed and under what rules.
I couldn’t agree more—except for one minor detail: Matt made his decision when he chose to distribute WordPress under the GPL. From then on, both he and any user of WordPress are bound by the terms of the license, and not by what anyone thinks. Matt doesn’t enforce the license: that’s for a court of law to do. Therefore, what he thinks at this point only has value, from a legal standpoint, if a competent court determines that the terms of the GPL agree with him.
This, incidentally, is one of the biggest concerns that I have with the GPL. It’s a license that enforces a very particular meaning of “freedom” whose nuances a developer may simply not understand. Case in point: Matt may well believe that themes must be released under the GPL as derivative works, but there is no real case law to back this belief. The FSF says so1, but they are less than intellectually honest by not admitting that they do not have the legal standing to back their claims.
The reason why I say that this is not a legal issue, therefore, is that, unless and until the WPF sues a theme developer on the issue of whether a theme or plugin that doesn’t incorporate wholesale code from the main project2 is a derivative work, this is a business issue that can deeply affect the future of WordPress if not handled correctly. Hence my points in the previous article.
One thing that many do not seem to understand that the enforcement of a contract (or a license) is, essentially, a failure of the contract itself. A contract exists so that two parties can have an understanding on how a business relationship should take place. If the contract is sufficiently clear and unequivocal, it should only ever be enforced if one of the parties maliciously and willfully breaches it and then refuses to cure the breach. If it is unclear and equivocal, as is the case here, the enforcement of a contract represents a failure to draft a proper agreement in the first place.
Let me say I disagree with the overall conclusion and opinion of the Mr. Tarbini as I understand it, but I do appreciate the points he raises.
GPL Motherfucker. Do You Understand It?
A thorny issue for me. Perhaps it is a failing on my part that despite reading the text (and rationale for GPLv3) I wouldn’t want to argue for high stakes in a court of law on the particulars of the GPL. Not only is the GPL complex, but copyright law is complex-squared.
Furthermore, it may just be my ego talking but I don’t put a lot of stock in GPL-interpretation by people who don’t do it for a living.
I’m not saying complexity or ambiguity is a GPL failure - perhaps the legal system itself makes it impossible to write something that is both understandable for a layperson and enforceable by a court.
I’m not being snarky.
GPL != Free Software
Another important distinction that doesn’t always get made: the GPL is not the be-all-end-all definition of Free Software. I look at the GPL as being the best attempt to enforce Free Software. I’m not aware of any license that does – or even attempts to do – a better job a promoting Free Software than the GPL.
Even so, consider the GPL is already on the third revision. For whatever reason earlier attempts fell short of the mark.
Therefore, I don’t think it’s out of line to realize that the GPL may fall short even if it may simultaneously be the best possible attempt – nor do I think such a problem invalidates either the GPL or Free Software.
Few things are without flaw or need of improvement.
Assume maliciousness and incompetence
There’s a famous bit about “never assume malice when incompetence explains”, but when dealing with GPL and Free Software, I think one must always assume malice and incompentence will be in play.
For example, business interests will always be looking for a way to get something for nothing (though never ever giving something for nothing! What are you – a COMMUNIST!) To them, exploiting Open Source seems like a free gold mine of research, development, software and support. Good business, maybe – but malicious.
Vast majority of “Open Core” falls in various degrees around this area. Rule of thumb: the louder and “Open Core” player trumpets “Open Source”, the further they are towards open-core-means-we-are-using-a-mit-licensed-tcp/ip-stack end of the spectrum.
Straight copying actual source code from WordPress into your theme that you insist isn’t a derivative work and isn’t under the GPL is malice too … in case you were wondering where to classify that.
Other area is incompetence. When Mr. Tabini asserts ”Matt made his decision when he chose to distribute WordPress under the GPL”, that’s incompetence. Matt never made a decision to distribute WordPress under the GPL – that decision was made for him, as he forked an existing GPL project.
Drafting an agreement
Having no choice ties into another problem with Mr. Tabini’s argument. Recall this bit:
If it is unclear and equivocal, as is the case here, the enforcement of a contract represents a failure to draft a proper agreement in the first place.
But! The parties (in this case) aren’t entering into a meeting-of-the-minds and drafting an agreement.
One party has pre-selected terms that – hopefully - covers his software in a manner he finds acceptable, and with the expectation that people using his software will act in a compliant manner. To him, he sees the GPL as enabling something.
The other party, though, is doing something very different – because he views that same license as something to be subverted or ignorned. To him, the GPL is disabling something.
If these two parties had sat down to draft an agreement, they would not agree on the GPL. That’s because one party wants to share code and the other doesn’t. The GPL isn’t a vehicle of agreement between those two parties.
A disagreement over a unique drafted agreement isn’t what happens when people have a GPL issue – it is invaribly someone who wants to benefit from GPL software, while not being bound the same requirements that made it possible and available to them in the first place.
If there is any failing on the part of the GPL here, it is not in the eyes of the second party – that person doesn’t want to share his code anyway. If there is a failing it is that the GPL has failed to enforce the terms that the first party expected – which I think are in line with the expectations of Free Software.
Commenting on comments to the commentary
As usual I find much interest in the comments. Consider this bit (sorry couldn’t find a direct link, it’s the second comment):
The second biggest problem is the attitude that there is only one correct interpretation of the license and if you don’t agree with that interpretation you’re breaking the law.
Eh? Isn’t the entire problem – assuming everyone is not acting malicously – that there isn’t one correct interpretation?
If there were “one correct interpretation”, then exactly how would one go about justify acting in defiance of that interpretation?

#1 by Marco on July 20, 2010 - 9:35 am
I respect your disagreement with my thoughts on the GPL, but I don’t think our positions are that far apart. My main point is: if you agree to something you don’t understand, you’re setting yourself up for trouble. When that something is not clear to start with, then you’re setting everyone up for trouble. The assumption that those who adopt the GPL (either by choice or by necessity) understand its implications is almost invariably wrong, not the least because there are some areas of the GPL that are simply unclear.
You and I may have completely different views of what “free” means, and a properly-written license should clearly and unequivocally explain to me (the licensee) what you (the licensor) intend my rights and obligations under the license to be. The GPL has too many grey areas and boilerplate definitions to be of value in every possible circumstance, and yet is being pushed by its proposers as an all-encompassing solution to preserving software freedom.
On the topic of people being forced to accept the GPL: abandoning your own judgment is never an excuse. Either one completely agrees with a set of terms and conditions and thoroughly understands what they mean, or he or she chooses a different project. Adopting a license and then forcing one’s own interpretation of its ambiguous provisions flies in the face of equity and fairness.
As I said: I don’t get to decide what the GPL means, nor does Matt, nor does the FSF. As far as derivative works are concerned, the meaning within the specific context of plugins and themes has not been decided in a court of law and is, therefore, ambiguous unless someone takes the time to write a proper license for it. We can continue to argue until the cows come home, or we can try and figure out a solution that is fair to everyone.
#2 by saulgoode on July 20, 2010 - 2:15 pm
The criticism that the terms and conditions of the GPL are “unclear and equivocal” is begging the question. If a developer is claiming that his software is not a derivative of someone else’s code then whatever licensing is offered for that code is inconsequential.
It is only after the code should be deemed derivative that the terms of the GPL come into play, and then the wording of the GPL is fairly straightforward.
The GPL is not to blame for any confusion that may arise over what constitutes a “derivative work”; the term obtains the exact same meaning under the GPL as it does under copyright law:
Any confusion that exists stems not from the wording of the GPL, but from copyright law itself.
#3 by Joe R on July 22, 2010 - 2:03 am
Thesis should look at the recent case in Australia:
http://en.wikipedia.org/wiki/Kookaburra_%28song%29#Copyright_status
A court decided that because the song “A land down under” contains a flute riff that sounds a bit like “Kookaburra sits on the old gum tree” therefore they had to give them 5% of the all the royalties from that song.
This is what “a derivative work under copyright law” looks like.
WordPress should get a lot more than 5% of Thesis’s royalties if they go to court.
Notice that WordPress won’t sue to enforce the GPL. They will sue to enforce copyright law. Nice and easy – the judges all understand copyright.
Thesis will then have to prove to the judge that they have permission to copy WordPress’s copyright code. They haven’t a prayer. Their lawyer will tell them to settle for what they can get. Wodpress will settle for their legal costs a 5 figure donation and the code and once again the GPL will never go to court.
#4 by Peter Kraus on July 23, 2010 - 6:21 am
GPL has been tested in the court already. Do some research before you post.