A comment from my last post asked me to back up the claim that settlements have lent weight to the validity of the GPL. I got some feedback from a friend and did a little research of my own and here’s a summary of the stuff that’s easy to find.

The developers of Busybox have been busy indeed:
March 6, 2008 BusyBox Developers and High-Gain Antennas Agree to Dismiss GPL Lawsuit
March 17, 2008 BusyBox Developers Agree To End GPL Lawsuit Against Verizon
July 23, 2008 BusyBox Developers and Supermicro Agree to End GPL Lawsuit
October 6, 2008 BusyBox Developers Settle Case With Extreme Networks

The GPL Linux Kernel has been defended in a European court verdict.

Many other successful settlements in favour of the GPL are available at gpl-violations.org.

Groklaw’s article “A GPL Win in Michigan” discusses how the US courts have found the GPL enforceable.

Sun Microsystems gets the GPL, even if it doesn’t suit them. in a CNET article from 2005, Jonathan Schwartz is quoted as not liking the GPL because of “the GPL provision that says source code may be mixed with other code only if the other code also is governed by the GPL”. Sun’s rather formidable legal team gets it: you can’t mix non-GPL code with GPL code and still comply with the GPL.

This is just the beginning. The SFLC has launched a suit against Cisco on behalf of the FSF. SCO descends further into bad joke status by attacking the GPL, with IBM on the other side. Any bets on who will take that one?

On the flip side, there’s nothing I could find where a challenge to the GPL was successful.