The following article from James A. Woods, one of the earlier
authors of compress, explains its relationship to the Unisys
patent on the LZW compression method:

From uunet!zephyr.ens.tek.com!uw-beaver!mit-eddie!wuarchive!usc!ucsd!ucbvax!agate!iacs!jaw Wed Aug  1 15:06:59 EDT 1990
Article: 1282 of gnu.misc.discuss
Path: alembic!uunet!zephyr.ens.tek.com!uw-beaver!mit-eddie!wuarchive!usc!ucsd!ucbvax!gate!riacs!jaw
From: jaw@riacs.edu (James A. Woods)
Newsgroups: gnu.misc.discuss
Subject: Sperry patent #4,558,302 does *not* affect 'compress'
Keywords: data compression, algorithm, patent
Message-ID: <1990Jul31.220935.1424@riacs.edu>
Date: 31 Jul 90 22:09:35 GMT
Organization: RIACS, NASA Ames Research Center
Lines: 69

#  "The chief defect of Henry King
    Was chewing little bits of string."

        -- Hilaire Belloc, Cautionary Tales [1907]

     As a co-author of 'compress' who has had contact with an attorney for
Unisys (nee Sperry), I would like to relay a very basic admission from Unisys
that noncommercial use of 'compress' is perfectly legal.  'Compress' is also
commercially distributed by AT&T as part of Unix System 5 release 4,
with no further restrictions placed upon the use of the binary, as far
as I am aware.

     From conversations with Professor Abraham Lempel and others, it 
appears that neither AT&T, Sun Microsystems, Hewlett Packard, nor IBM
are paying any sort of license fees to Unisys in conjunction with patent
#4,558,302.  It may be true that some organizations are paying fees for
data compression technology licensed from one or more of the many holders
of compression patents, but this is all independent from 'compress'.

     In particular, I received a letter at NASA dated October 1, 1987 from
John B. Sowell of the Unisys law department, informing me for the first
time that some form of LZW was patented.  I naturally expressed
skepticism that an algorithm could be patented (a murky legal area
which remains so), stated that 'compress' is not identical to LZW,
and in fact was designed, developed, and distributed before the ink
on the patent was dry.  Several telephone conversations later, Mr. Sowell
intimated that they would *not* seek any fees from users of 'compress'
but instead were signing licensees for hardware implementations of LZW.

     So, regardless of what you believe about a shady legal area, if anyone
from Unisys contacts you to extract tribute for the use of 'compress', please
tell them that, first, it is not theirs to begin with, and, second, there is
someone who will testify in court about the conversation above.
It is not even clear if anyone can "own" 'compress', since original developer
Spencer Thomas, myself, and others placed the code in the public domain
long before the adoption of the Berne copyright convention.

     In light of the events above, it seems that the Free Software
Foundation is being unduly paranoid about the use of 'compress'.
Now I can well believe that FSF is more likely to be a legal target
than a behemoth like AT&T, but if they are simply redistributing
untouched free software developed years ago in the public sector,
I see no problem.

     Aside:  I am investigating, possibly for a case history to be
recycled to USENET, the particulars of data compression patents.
I am aware of the following patents: IBM's Miller-Wegman LZ variant,
those of Telcor and ACT [losing candidates for the British Telecom modem
standard], James A. Storer's work on limited lookahead as explicated in his
text "Data Compression (methods and theory)", Computer Science Press, 1988,
and the various patents pending associated with the Fiala and Greene
CACM article of April, 1989 on textual substitution methods.
If you have any lore, send it this way.



                    Sincerely,

                    James A. Woods
                    NASA Ames Research Center (RIACS)
                    jaw@riacs.edu (or ames!jaw)


P.S.  The algorithm patent issue certainly is a "topic A" at the moment.
One useful reference is the review article by Anthony and Colwell --
"Litigating the Validity and Infringement of Software Patents" in
Washington and Lee Law Review, volume 41, fall 1984.  I know Robert Colwell
personally.  As a practicing patent attorney, he tells me that, at a minimum,
use of an invention "for research purposes" is legitimate.