There was a major open source legal development this week and surprisingly, it did not involve the string of BusyBox lawsuits, which included settlement from mobile and telecom giant Verizon in March 2008. Instead, the latest open source victory involves a federal appeals court ruling that basically upholds the idea and enforcement of ‘copyleft.’

The ruling, which centered on the Artistic License, made it clear that regardless of whether software is open source or proprietary, its creators have a right to attach requirements and conditions that govern its use and distribution. So to those who have argued that the GPL or other open source licenses might be thrown out of court, there is now more concrete proof. Open source software and its licensing are not some strange legal realm. Instead, GPL and other open source licenses base much of their meaning on existing, accepted laws, particularly U.S. copyright law and with GPLv3, international copyrigt law.

During the BusyBox GPL enforcement cases over the last year, there have been calls for actual courtroom hearings rather than settlement. The thinking is this would go further to solidifying the legality and legitimacy of the GPL and open source licensing in general. However, I still believe that the settlements, particularly from the likes of Verizon, do as much to bolster open source licensing. Now it appears open source supporters can have it both ways given the string of BusyBox settlements and the recent ruling that reinforces one of the basic tenets of open source, copyleft, in U.S. legal books.