This article in Newsweek is a nice summary of Thomas Tamm's work as a whistle-blower. The U.S. Government set up rooms in major telecoms that allowed them to wiretap virtually everyone in the United States. Is was illegal, as wiretaps require a court order.
So if it was illegal, why isn't anyone in jail? Congress passed a law giving retro-active immunity to telecoms. The constitutionality of that law is in question.
Tamm's life has been ruined, with mounting debt from hiring lawyers to defend him. The government would like him to plead guilty for disclosure of classified information. The fact that the U.S. was breaking the law was classified.
Technological advances in data-mining have created new tools that can be used for law enforcement. Tools that our current law does not support. Have we gotten anything useful by having the government wiretaps? Frontline did a great piece on how New Year's Eve parties were almost canceled in Las Vegas because of a translation error with a wiretap. But I'm unaware if any legitimate plot has been uncovered in return for no longer requiring a warrent.
We need to have a rational conversation as a country about the new tools technology supplies our society, and how to balance it against citizen rights.