Are WordPress themes GPL?

The world of Open Source software has always interested me in great detail and people charging for themes and various plugins for gpl based content management systems has never bothered me at all.  But is it legal to do so?

An interesting post has been made on the WordPress blog which doesn't ask the question whether themes are GPL but instead reiterates the fact that: Themes are GPL, too This is also the complete opposite to Joomla's stance on the very same issue.

There have been some questions in the community about whether the GPL applies to themes like we’ve always assumed. To help clarify this point, I reached out to the Software Freedom Law Center, the world’s preeminent experts on the GPL, which spent time with WordPress’s code, community, and provided us with an official legal opinion.

The response from  James Vasile of the Software Freedom Law Center:

In conclusion, the WordPress themes supplied contain elements that are derivative of WordPress’s copyrighted code. These themes, being collections of distinct works (images, CSS files, PHP files), need not be GPL-licensed as a whole. Rather, the PHP files are subject to the requirements of the GPL while the images and CSS are not. Third-party developers of such themes may apply restrictive copyrights to these elements if they wish.

Finally, we note that it might be possible to design a valid WordPress theme that avoids the factors that subject it to WordPress’s copyright, but such a theme would have to forgo almost all the WordPress functionality that makes the software useful.

James Vasile
Software Freedom Law Center

Personally, I think if you buy a theme for a GPL CMS, you are paying for someones artistic ability - and that should definately not be GPL'ed.  A theme requires GPL code in order to work with an Open Source CMS - thats just the way it is.  The official WordPress response seems to display the fact they do not want anyone making money from their product in the way they would like.  I am open to anyone who can explain why I should not think in this regard.

Brian Gardener, the creator of some spiffy wordpress themes with his studiopress collection has  intruiging perspectives on the topic:

PHP in WordPress themes must be GPL, artwork and CSS may be but are not required.

It seems that even before the posting of the response that Matt was given from the Software Freedom Law Center, other developers such as iThemes and WooThemes had already decided it was wise to move their licenses over to the GPL.

There you have it.

And as Matt puts it, WordPress has chosen to celebrate those who are developing GPL themes with a brand new Commercially Supported WordPress Theme page. Which, of course is a follow through to a promise that Matt made nearly a year ago.

This also clearly illustrates Matt’s view that people can (and will be endorsed if they do it with the GPL License) make money using WordPress.

Fair enough I suppose, though this does seem like a contradiction of the GPL licence as a whole - Remember the whole raging Joomla gpl extension debate?

Also check the Woothemes response.