IBM is being sued for attempting to prevent customers from using third party software on its mainframes.
Neon Enterprise Software alleges that IBM is telling its customers not to use its software on its mainframes, an accusation that Big Blue is denying.
The case, filed in a Texas district court, alleges that Neon's zPrime software lets IBM customers reduce licensing fees by more than 50 percent by shifting workloads to different processors.
But, according to an IBM representative, quoted in the Wall Street Journal and Bloomberg, Neon's software subverts Big Blue mainframes processing power. It likened Neon software to the actions of a homeowner tampering with an electricity meter.
That kind of argument may not wash - IBM is already being investigated for holding a monopoly in the mainframe market by the Department of Justice.
IBM has a history of protecting its mainframe business. A consent decree issued in 1956 was only lifted in 2001.