The NSA's business is 'information dominance,' the use of other people's secrets to shape events.

The Obama administration has provided almost no public information about the NSA's compliance record.

In the urgent aftermath of Sept. 11, 2001, with more attacks thought to be imminent, analysts wanted to use 'contact chaining' techniques to build what the NSA describes as network graphs of people who represented potential threats.

NSA surveillance is a complex subject - legally, technically and operationally.

I have no evidence of any relationship between IRS and NSA.

Companies that receive government information demands have to obey the law, but they often have room for maneuver. They scarcely ever use it.