Unix System Laboratories (USL) was originally organized as part of Bell Labs in 1989. USL joined with the UNIX Software Operation, also a Bell Laboratories division, in 1990. It assumed responsibility for Unix development and licensing activities. It then became a separate wholly owned subsidiary, formed, owned, and operated by AT&T Corporation, the parent company of Bell Labs. Its CEO was Roel Pieper.
Unix System Laboratories was the plaintiff in the USL v. BSDi lawsuit initiated in 1992 against Berkeley Software Design, Inc and the Regents of the University of California over copyrights and trademarks related to Unix. USL asked the court for a preliminary injunction that would bar BSDi and the UC Berkeley from distributing the NET-2 software until the case was concluded. USL v. BSDi was settled out of court 1993 after the judge expressed doubt as to the validity of USL's claims.
In June 1993, Novell purchased USL and all of the Unix assets, including all copyrights, trademarks, and licensing contracts.