It's really a case of contract law. Yet the SCO versus IBM case has raised the ire of many, along with the level of confusion, in an already noisy software market.
Just in case you've tried to ignore this mess, IBM has a license from SCO (then Santa Cruz Operation, now SCO Group) for the basis of IBM's AIX Unix-based operating system. SCO claims that IBM misappropriated source code from the proprietary Unix into IBM's Linux offering, which was in turn made available to the world through the usual Linux GNU Public License (GPL). SCO wants billions for this transgression. The case is evolving slowly, as SCO is being very secretive about infringing source code.
These issues aren't new. They bear some resemblance to a 10-year-old case that AT&T brought against Berkeley Software Designs Inc. (BSDI) and the Regents of the University of California through its subsidiary, UNIX System Laboratories Inc. (USL). As a matter of note, BSD (Berkeley Software Distributions) and its variations such as NetBSD and FreeBSD are rewritten open-source versions of Unix V32.
The case between USL and BSDI and company revolved around the allegation that the initial rewrite, called Net2, still incorporated code from V32. Albeit, it was a very small portion, especially since BSD had turned into a very large system that dwarfed its UNIX parent in size and scope. It turns out that UNIX actually contained BSD code! The suit was eventually settled with USL paying court costs and BSD not requiring a UNIX license.
The plot twists and turns as USL was eventually sold to Novell, who gave the Unix trademark to the Open Group (www.unix.org). The Open Group is responsible for the Single Unix Specification, but Novell retains ownership of Unix and the associated copyrights and patents. It licensed Unix to the SCO Group that sells UnixWare and, in turn, licenses Unix to companies such as IBM.
So what claim does SCO have if Novell owns the rights to the source of the alleged infraction? SCO claims it's a "successor in interest," given its contracts with Novell and IBM. It will take many legal minds to untangle the claims, counterclaims, contracts, and so on.
The adventure through these "twisty little passages, all alike" became a concern to others because of the potential impact on Linux. Luckily, the overall impact may be minimal to none. As an added twist, the SCO Group was formerly known as Caldera International and has its own version of Linux distributed under GPL much like other Linux distributions. Caldera Linux likely included the source code under consideration. Caldera Linux wasn't pulled from the market until well after the case was in full swing.
What could be an even more interesting outcome of potential disclosures is whether Unix employs any open-source code. The BSD license is more liberal than Linux's GPL, but it still requires annotations about a code's heritage.
The motivation for the SCO versus IBM case may be somewhat suspect. SCO's stock price was well under $1, but it has risen to over $10 with the announcement of the case. It's still a far cry for the stock price from over two years ago, which exceeded $100, and definitely not in line with the current product offerings.
For the SCO Group, the result of the case will probably be the difference between a windfall and obscurity. For the rest of us, the implications are clear. It matters little if you're dealing with open-source or closed-source software. Intellectual-property management remains critical to the long-term stability of a company and its products. The importance of software audit trails should not be overlooked. For Linux users, this may be a non-event.