“We have not identified a single instance involving a threat to the United States in which the telephone records program made a concrete difference in the outcome of a counterterrorism investigation,” said the report, a copy of which was obtained by The Washington Post. “Moreover, we are aware of no instance in which the program directly contributed to the discovery of a previously unknown terrorist plot or the disruption of a terrorist attack.”

Claim: NSA mass surveillance keeps us safe. Fact: In over 10 years, not 1 life saved in US. https://t.co/vzJmBec2Yq pic.twitter.com/ad0MTvuZr7

— Edward Snowden (@Snowden) October 11, 2015

Source: Independent review board says NSA phone data program is illegal and should end – The Washington Post