SCO can sue their own customers in Germany.

[OffTopic1]

"SCO Group GmbH is prohibited to threaten to sue Linux users unless they bought SCO Linux or Caldera Linux."

SCO Backs Off in Germany - Out-of-Court Settlement with Univention Reported

 

[ElFenix]

what grounds would they have to sue users who legally bought their product?

 

[B00ne]

Either my english is bad or they (the website) got the settlement totally wrong:
The german text says:

- SCO will refrain from claiming that Linux operating systems contain unlawfully aquired intellectual property of SCO Unix
- futher the settlement prohibits SCO from threatening end users operating Linux to be accountable for breach of SCO intellectual property
- also SCO is not allowed to say that Linux is an unauthorized UNIX derivative
- last but not least: unless the purchased OS are SCO Linux or Caldera Linux, SCO will refrain to claim that Linux users will be prosecuted by SCO (whatever that means)

After this settlement SCO will refrain from publically claiming that proof regarding the breach of IP will be presented unless SCO presents such proof within 1 month after the settlement