eBay v. MercExchange
2006 US Supreme Court case holding that winning a patent suit does not automatically entitle you to shut down the other side's product.
MercExchange held patents on fixed-price sales in online auctions, and in 2003 a jury found eBay liable for infringement. The Federal Circuit then applied its long-standing general rule: a patentee who wins gets an injunction, more or less as a matter of course.
The Supreme Court threw that rule out unanimously in May 2006. Patent cases get the same four-factor test as everything else — irreparable harm, inadequate damages, balance of hardships and the public interest. In a concurrence, Justice Kennedy singled out firms that use patents mainly to extract licensing fees, noting that the threat of an injunction had become a bargaining weapon. That was exactly the leverage NTP had used against BlackBerry that spring. Afterwards, damages were usually the best a patent troll could hope for.