USL v. BSDi

USL v. BSDi was a lawsuit brought in the United States in 1992 by Unix System Laboratories against Berkeley Software Design, Inc and the Regents of the University of California over intellectual property related to the Unix operating system. The case was settled out of court in 1993 after the judge expressed doubt in the validity of USL's intellectual property, with Novell (who by that time had bought USL) and BSDi agreeing not to litigate further over the Berkeley Software Distribution (BSD), which would later develop into a range of BSD distributions, each tuned to its own specific audience's strengths and markets.

The suit has its roots at the Computer Systems Research Group (CSRG) at the University of California, Berkeley, which had a license for the source code of UNIX from AT&T's Bell Labs. Students doing operating systems research at the CSRG modified and extended UNIX, and the CSRG made several releases of the modified operating system beginning in 1978, with AT&T's blessing. Because this Berkeley Software Distribution (BSD) contained copyrighted AT&T Unix source code, it was only available to organizations with a source code license for Unix from AT&T.

Students and faculty at the CSRG audited the software code for the TCP/IP stack, removing all the AT&T intellectual property, and released it to the general public in 1988 as "Net/1", under the BSD license. When it became apparent that the Berkeley CSRG would soon close, students and faculty at the CSRG began an effort to remove all the remaining AT&T code from the BSD and replace it with their own. This effort resulted in the public release of Net/2 in 1991, again under the BSD license. Net/2 contained enough code for a nearly complete UNIX-like system, which the CSRG believed contained no AT&T intellectual property.

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