Please note that if you believe it is theft for a person to take a WP template and use it for their own means, whether for redistribution within a WordPress file or to remove footer code etc.. then in affect you are stealing the very thing that WP was built on, thus being an open source license for individuals to use modify and redistribute however they wish. If a WP theme hooks into WordPress, like they all do in order to function appropriately as web templates, then you are fundamentally giving away your rights to that template. You have the liberty to say that your template is copyrighted etc…, but this cannot be forced and it is not a legal obligation for WP users to abide by. I would say that if anyone has a problem with others redistributing their work then they should not build their work for an open source platform such as WordPress. I do understand the hard work and time that has went into the production of these templates, and understand the dismay at not receiving any royalties, but that is the choice that web template developers make. Additionally a stylesheet can be easily modified to become your own, as it is just about changing the tags, a few mark-ups etc… So i don’t believe style-sheets within WP themes have much to go on either.

Brad, Andrew and whoever else argues with “legal issues” – that’s plain wrong.

For one, the GPL itself does not restrict mixing with every other license, just with “incompatible” licenses. (There is a list of compatible liceses at http://www.gnu.org/licenses/license-list.html#GPLCompatibleLicenses)

But more importantly, the GPL covers distribution, not usage. As long as GPL and “non-free” stuff are distributed separately, and only used together at the end user’s site, there are absolutely no legal issues. This is legal reality, no matter what the mysterious “reputable source” (mentioned elsewhere in the comments) says about it.

(In fact, the only truly reputable source on this matter is GNU and the FSF, and perhaps lawyers specialized in the open source licensing topic.)

I understand that folks at WP.org would love to force everyone to take on their view of licensing models, and they are pretty militant about it, but that does not change the fact that it’s not the GPL that makes the restrictions, but them, and only them.

So Sadish, from a legal perspective, you can safely put your themes under any license you want. It’s just that you’ll have to live with the fact that the WP hardliners are not going to love you for it. If you can live without their love, there’s no reason why you should not do your licensing your own way.

The GNU GPL is written to guarantee four basic freedoms for the user:

0 – The freedom to run the program, for any purpose
1 – The freedom to study how the program works, and change it to make it do what you wish
2 – The freedom to redistribute copies so you can help your neighbor
3 – The freedom to distribute copies of your modified versions to others

The license is intentionally viral, as its purpose is to preserve those freedoms as long as copyright exists on all works derived from GPL (or combined with GPL) code.

The GPL is also very, very specific about the nature of any work. A program (or theme, or style sheet, or whatever is covered by the license) is either an original, combined or derived work.

Using WP code in any theme makes the end result a _combined_ work. Your code, plus WP code is combined and executed in the same address space by PHP. Therefore, any theme using WP functions or framework (i.e., it depends on WP) must be compatible with the GNU GPL itself. A lot of the creative commons licenses are compatible, as long as they do not restrict what you can modify in the theme, including removal of HTML code like footer links. So I agree, partly, themes do not have to be GPL; themes must be _compatible_ with the GPL, meaning they must be equally or less restrictive. The 4 clause (revised) BSD license is fully compatible with the GPL2 and 3, however the GPL prevails if you distribute it.

Technically, your themes should not combine with GPL code, because the two licenses are not compatible. However, since your themes are not distributed with WordPress, and do not contain the actual (functional) implementations of the functions you use from WordPress, there is nothing to say you can’t distribute them (yet).

The legal issues surrounding this are solid, have been proven in court countless times and definitely apply. However, this does not, as I noted, make your business untenable. It simply means nobody can distribute WordPress with your theme installed.

IANAL, but I deal with software licensing issues professionally on a daily basis, its my job to integrate FLOSS into our business, appliance products, etc.

There is an analogy with Linux. Linux kernel is GPL’ed and it provides API for device manufacturers to write their device drivers. However the drivers can be non-GPL licenced. The usage of API doesn’t enforce GPL licence on the software that uses API. There are plenty of proprietary software for Linux.

Back to WordPress. I believe if theme doesn’t change or tamper with WordPress code and just merely uses WordPress hooks (WordPress API) then it can be non GPL’ed. So every WordPress derivative CMS must be GPL’ed, but there may be add-ons to the CMS (themes) which can be non GPL’ed.

I am not a lawyer. This is only my personal opinion about this legal issue.

1. Any file in a WordPress theme that calls a WordPress function *has* to be licensed under the GPL.

2. Any file in a WordPress theme that calls a WordPress function does not have to be licensed under the GPL.

3. The GPL is not a ‘freedom-based’ licence. It is incredibly restrictive, but it is presented as a ‘freedom-based’ licence presumably because it sounds better. See “the GPL is what has kept the freedom in software” as an example.

4. “The adoption of GPL has made WordPress the huge success it is today.” This implies that if any project wants to be a success, it should use GPL. This is obviously false. WordPress was forced to use the GPL because it was built upon the work of another project which used the GPL.

5. “you may license your creations (i.e. WP themes) whatever you want.” This is not the case. See points 1 and 2.

6. The php code in WordPress themes is the least important part of the theme. The css, artwork, and html are. In a matter of minutes any WordPress theme could be converted to a standard template by removing WordPress api calls.

7. Even though the php code is the least important part of the theme (point 6), the GPL licence is still forced on any php files that make use of WordPress code.

8. My problem with this is that themes as a collection are not automatically GPLed. There should be a way to ensure attribution for css and artwork if that is what the theme creator wants. The GPL makes this impossible, without either hurting the end users or the creators.