Federal judges approve about 30,000 secret warrants to spy on people in the USA every year, and the innocent probably will never know they were watched, says a U.S. jurist involved in issuing the orders.

Magistrate Judge Stephen Smith writes in a new paper, highlighted by Ars Technica, that the 2006 total outstripped the entire output of the Foreign Intelligence Surveillance Court since it was created in 1979, and the number is probably growing.

The secret orders are authorized by the Electronic Communications Privacy Act of 1986, known as ECPA. Smith writes that the volume of such cases "is greater than the combined yearly total of all antitrust, employment discrimination, environmental, copyright, patent, trademark and securities cases filed in federal court."

The warrants and the court's proceedings are not open to public scrutiny. A three-judge panel reviews denials of applications for the warrants, but the court is not adversarial or open, and many orders are never unsealed.

Here are some of Smith's findings, which will be published in the Harvard Law & Policy Review:

These electronic surveillance orders ... grant law enforcement access to the electronic lives of our citizens -- who we call, where we go, when we text, what websites we visit, what emails we send. Unlike most court orders, electronic surveillance orders are permanently hidden from public view by various ECPA provisions, including sealed court files, gag orders, and delayed-notice. It's as though these orders were written in invisible ink -- legible to the phone companies and electronic service providers who execute them, yet imperceptible to targeted individuals, the general public, and even other arms of government, including Congress and appellate courts. This regime of secrecy has many unhealthy consequences: Congress lacks accurate empirical data to monitor the effectiveness of the existing statutory scheme and adapt it to new technologies; appellate courts are unable to give effective guidance to magistrate judges on how to interpret ECPA's complex provisions in light of changing technology; and citizens are not informed about the extent of government intrusion into their electronic lives. With Congress on the sidelines, appellate courts not engaged, and the public in the dark, the balance between surveillance and privacy has shifted dramatically towards law enforcement, almost by default.

To get to his 30,000 estimate, Smith combined an earlier government survey with data from his own court's docket, Ars Technica notes.

Smith calls for "structural changes" in the law to "eliminate unnecessary secrecy," including an end to "automatic gagging" and sealing orders. He suggests a publicly available "warrant cover sheet" that features basic information about every electronic surveillance order.