If you've been with us a very long time, you'll remember this case from back in 2004. Lexmark made printers and ink cartridges and in order to stop people using 3rd-party replacement cartridges they jiggered up a UI that read information from a chip in the (their) ink cartridge. Static Control figured out what signals the printer wanted to get and made its own chipped cartridges that could be used. Lexmark sued, initially under a novel DMCA theory that tried to prevent SC or anyone else from reverse-engineering the printer-cartridge interface. They lost.

The case went back down to the trial level, Lexmark lost again, appealed up to the Sixth Circuit again, lost again. The case went back down. Meanwhile SC made new cartridges and started its own suit looking for a declaratory judgment that it was non-infringing. The suits got consolidated, and a jury trial was held, at which Lexmark lost again, and again appealed to the Sixth, which has just slapped them down again.

If anyone starts to think this more resembles a game of handball than an intellectual property case, I can't blame them.