SCO is suing IBM over its version of Unix, AIX, and is threatening to revoke IBM's licence to sell the widely used operating system from 13 June.
The software company, which acquired software code and licensing rights to Unix System V technology - the basis of all commercial versions of Unix - in 1995, has accused IBM of misappropriating trade secrets, unfair competition and breach of contract.
SCO claims the software and services giant channelled parts of its proprietary Unix code into the open source community, undermining demand for Unix. IBM denies these allegations.
Michael Bywell, a partner in the technology, media and communications group at law firm DLA, said AIX users and users of Linux-based products supplied by IBMwould inevitably suffer a period of disruption if IBM loses the case and SCO revokes IBM's Unix licence. IBM could even find itself open to claims from AIX users.
"UK users will probably have an indemnity in their contract covering infringement of intellectual property rights so potentially they could bring claims against IBM," he said.
The case could also have a disruptive impact on the open source community and users of SCO Unix could be left high and dry, said Bywell.
Prominent SCO Unix users in the UK include financial services firm AXA UK and retailers Littlewoods and Woolworths. AIX is popular throughout the financial services and retail sectors.
IBM bought its Unix licence from developer AT&T in 1985. SCO claimed the licence required the services giant to hold the Unix code in confidence.