The Digital Millennium Copyright Act (DMCA) makes it illegal to break software locks. Under that theory, Lexmark sued a competitor, Static Controls, for making compatible printer cartridges because refilling the cartridges necessitated resetting the cartridge software, and doing that meant breaking the lock that intended to keep you from refilling your cartridge. Get that: they claimed, basically, that the printer cartridge was a copyrighted work, and that by refilling it, you were pirating it.
Anyway, this is so much bullshit, it makes your head spin. And as of today, the appeals court agrees: Lexmark can't use the DMCA to prop up its business-model of charging you a 1000 percent markup on its inkjet carts. Neener, neener, neener.