1) Consumer buys patented toner cartridge (probably bogus/obvious patent, but that's not at issue here)
2) Consumer returns toner cartridge to recycler.
3) Recycer refurbishes cartridge and re-sells it to someone else.
Lexmark wants to say that after you've used the toner cartridge, you can't give it to someone else, because they didn't license the patent to someone else. The law isn't clear at all on the topic, so the court could go either way. Even the supreme court seemed a bit confused by the situation (this is based on reading the article, not reading the actual law documents).