You can't - the government's argument is that you can use the metadata to usefully augment other intelligence/investigative techniques without undue violation o

You can't - the government's argument is that you can use the metadata to usefully augment other intelligence/investigative techniques without undue violation of the privacy of, well, everybody whose metadata you've collected. If you know a terrorist has used a particular phone number you can use the historical metadata record to try to identify the terrorist's potential associates. Ex-NSA head Michael Hayden claims that's the way the data is used. http://www.npr.org/blogs/thetwo-way/2013/06/09/190092800/bush-era-nsa-chief-defends-prism-phone-meta-data-collection http://www.npr.org/blogs/thetwo-way/2013/06/09/190092800/bus... Given the very limited number of hard, verifiable facts about these programs, whether you believe or disbelieve this explanation is almost a matter of faith.