"Conventional wisdom among free software and open source
developers has long warned that software patents could corrupt and
disrupt good software projects. The GPL mentions such a risk, for
example. While only a few patents have actually stopped the
development of some software (Unisys' GIF patent, the patented LZW
algorithm, and Fraunhofer's MP3 patent), the risks involved in
developing software in a patent-haunted world remained unclear.
"Though many developers prefer to ignore patents, the current
laws (at least in the U.S.) provide minimal legal defense for
unwitting infringements. Worse yet, though a project may have
pedigreed and documented prior art that could easily convince a
court to overturn a patent, the cost of such an action is out of
reach for most developers--and many companies..."