1999.12.01 03:15 "Re: libtiff 3.5.3 release.", by Bob Friesenhahn
Xpdf (PDF viewer) author goes to the trouble of not using LZW decompression in Xpdf itself, but exec's system's "uncompress" to do the decompression. I believe he must have been a target of "Unisys patent enforcement."
I am not aware of any open source author being sued (or even contacted) by Unisys regarding LZW in the sources. Removal of LZW in the open source community was first driven by the philosophies of Richard Stallman and the FSF and led to the creation of gzip, zlib, and libpng. Most recently Unisys has expanded their demands on their web site to mention open source software and web sites. This has resulted in web sites switching to PNG, and additional open source packages removing support for LZW compression.
Does anyone know for a fact that an open source author has been threatened by Unisys's laywers?