The Columbia Law School professor and GC of the FSF describes how SCO's Las Vegas presentation purporting to identify code from the Linux kernal copied from UNIX Sys V source code was promptly demonstrated to be untrue. The more interesting aspect is how IBM has painted SCO into a corner with its counterclaims.
SCO's legal situation contains an inherent contradiction. SCO claims, in the letters it has sent to large corporate users of free software and in public statements demanding that the users of recent versions of the kernel take licenses, that the Linux program contains material over which SCO holds copyright. It also has brought trade secret claims against IBM, alleging that IBM contributed material covered by non-disclosure licenses or agreements to the Linux kernel. But it has distributed and continues to distribute Linux under GPL. It has therefore published its supposed trade secrets and copyrighted material, under a license that gives everyone permission to copy, modify, and redistribute. If the GPL means what it says, SCO loses its trade secret lawsuit against IBM, and cannot carry out its threats against users of the Linux kernel.
But if the GPL is not a valid and effective copyright permission, by what right is SCO distributing the copyrighted works of Linux's contributors, and the authors of all the other copyrighted software it currently purports to distribute under GPL? IBM's counterclaim against SCO raises that question with respect to IBM's contributions to the Linux kernel. Under GPL section 6, no redistributor of GPL'd code can add any terms to the license; SCO has demanded that parties using the Linux kernel buy an additional license from it, and conform to additional terms. Under GPL section 4, anyone who violates GPL automatically loses the right to distribute the work as to which it is violating. IBM therefore rightly claims that SCO has no permission to distribute the kernel, and is infringing not only its copyrights, but those of all kernel contributors. Unless SCO can show that the GPL is a valid form of permission, and that it has never violated that permission's terms, it loses the counterclaim, and should be answerable in damages not only to IBM but to all kernel contributors.
SCO and its predecessor, Caldera, have benefited enormously from the protections of the GPL. Thanks to the GPL, SCO has been able, for example, to use the invaluable work of compiler designers and implementers around the world who have made GCC the premier cross-platform C compiler. Customer applications run on SCO's Sys V Unix because of GCC, to which SCO contributed modifications particular to its system, and for which it assigned copyright to the Free Software Foundation. Caldera and SCO could not have marketed a usable operating system product without the contributions of the free software community. SCO was happy to take the benefits, but it has unethically sought to avoid its responsibilities.