The Supreme court in a 7-1 decision found that consumers can do what they want with the printers they buy, despite Lexmark forcing buyers to "sign" a "post-sale restriction" contract that the buyer won't tamper with their patented product after they buy it.
The case is "Impression v Lexmark."
Lexmark makes two similar types of printers: the cheaper one comes with ink cartridges that have a chip on them that prevents users from refilling them and putting them back in the printer, so the user has to go buy a new one from a store. Impression removes the chip so users can refill their cartridges.
Lexmark sued, saying that infringes on their property rights (which they said they maintained post-sale) that prevented third parties from modifying or repairing their products.
The court reasoned that if companies could maintain property rights preventing modification and repair after a product was sold, pretty much every repair shop in the country could be sued, the "smooth flow of commerce" would be impaired, and all parties involved would end up harmed.