When Americans expressed outrage last week over the seizure and surveillance of Verizon's client data by the National Security Agency, President Obama responded: "In the abstract, you can complain about Big Brother . . . but when you actually look at the details, I think we've struck the right balance."

How many records did the NSA seize from Verizon? Hundreds of millions. We are now learning about more potential mass data collections by the government from other communications and online companies. These are the...