U.S. spy agency abandons controversial surveillance technique

By Dustin VolzWASHINGTON (Reuters) - The U.S. National Security Agency said on Friday it had stopped a form of surveillance that allowed it to collect without a warrant the digital communications of Americans who mentioned a foreign intelligence target in their messages, marking an unexpected triumph for privacy advocates long critical of the practice.The halt is among the most substantial changes to U.S. surveillance policy in years and comes as digital privacy remains a contentious issue acros