The open source patent war
Due to the fact that Linux is free software and belongs to no-one, it is often assumed that Linux is "surrounded by legal uncertainties."
However, Linux is no more or less prone to legal uncertainties, by which we usually mean potential patent infringements, than any other software application or platform. The problem is not the software nor the license, but the legal framework within which the software industry operates. Software patents have become part of the standard software industry model but are antithetical to the objectives of open source software and are seen as problematic for the good health of future software development by free software developers.
The problem for proprietary software companies is that free software pulls the rug from under traditional software models. By definition free software is collaborative. Numerous individuals, hardware companies and academic establishments contribute to the code that is contained in a Linux distribution, and all have a vested interest in its success. The customer gains because the software is free and tends to be more adventurous, versatile and secure. The only potential loser is the traditional software vendor.
So it has been suggested, sometimes by the software vendors themselves, that those who are threatened by the competitive success of open source might seek to challenge Linux through the courts, on the grounds that the software, and Linux in particular, might include "stolen IP", and infringe the patents or copyrights of others. This is unlikely. The accusation has often been made, but the code is there for all to see, and no convincing evidence has ever been presented of any infringement.
The more likely action is of the type affected by Microsoft in its recent agreement with Novell.