This is a story that is years in the making.

In 2003, a company called SCO sued IBM for supporting Linux. SCO's contention was that IBM put Unix code into Linux. This raised some legal questions about the use of Linux in some circles, although most saw this as a desperate attempt to ruin Linux without any real legal basis. This was pretty much confirmed when SCO refused to be specific in to court about what actually was "stolen" from Linux. One of the judges at one point compared the situation to a store accusing a person of shoplifting, and as "proof" the store hands in a copy of their own catalog and say simply that the item shoplifted was in the catalog somewhere, and left it to the defendent to prove they didn't shoplift anything. Most of SCO's claims were tossed out of court before reaching trial.

Before the trial could move forward, however, Novell stepped into the fray. According to Novell, they had a contract with SCO allowing SCO to use Unix copyrights. However, according to their lawsuit against SCO, Novell owned the copyrights to Unix, not SCO. Today, a U.S. District Court ruled that Novell is correct, they own Unix and SCO has no claims to the copyrights or the intellectual property.

Considering the fact that Novell owns the copyright and intellectual property for Unix, and that Novell has their own Linux distribution (SUSE Enterprise Linux), I would say they are not going to be interested in suing IBM for copyright infringement.

Of course, we still have to put up with Microsoft accusing Linux of stealing intellectual property from them, but like SCO, they have yet to offer proof or examples of what was actually stolen.

http://www.linux-watch.com/news/NS4446359842.html

Of course, there are a lot of little issues that pop up in this whole thing that has been going on for years, including the discovery that Microsoft, while not taking a publicly active role in the lawsuit, did provide SCO with millions to help pay for legal expenses during this process.