Some patent battles are hard fought, as evidenced by Baxter's ($BAX) recent legal squabble with Fresenius Medical Care. In May, the U.S. Supreme Court declined to hear an appeal filed by Baxter, which sued Germany-based Fresenius in 2003 for allegedly infringing its patents on a kidney dialysis device. Baxter scored a victory in 2012, winning a $24 million judgment over Fresenius. But one year later, the U.S. Patent and Trademark Office canceled Baxter's patent, prompting a federal court to toss out the dispute.

Baxter appealed the decision, asking the nation's high court whether judges should defer to the Patent and Trademark Office during a patent dispute. Device heavyweights such as Medtronic ($MDT) encouraged the Supreme Court to hear the case, arguing that the current system prolongs court proceedings through dual-track litigation. But the company's complaints fell upon deaf ears, leaving the original ruling by the U.S. Court of Appeals for the Federal Circuit intact.

For more:
Supreme Court won't hear Baxter v. Fresenius patent case, irking industry
Fresenius beats back Baxter's patent suit