In 2004, Novell claimed it owned the rights to Unix after SCO had decided on litigation a year earlier to enforce Unix copyright.

In 2003, SCO claimed that Linux was an illegal derivative of the Unix code, which SCO said it had purchased from Novell. , picking IBM as its first target in a $1 billion copyright infringement suit claiming Big Blue had violated SCO’s rights by contributing Unix code to Linux.

Microsoft joined the fray shortly thereafter, agreeing to license Unix code from SCO and then using the association to fuel confusion over open source licenses and the liability they could carry for corporate users.

SCO eventually sent letters to some 1,500 large companies, warning them that their use of Linux could infringe on SCO’s intellectual property. SCO then turned on Novell when it claimed Unix ownership.

But that did not go well for SCO