In early 2003, an AT&T technician named Mark Klein noticed something unusual at one of the company’s network facilities in San Francisco: A new “secure room” had been set up in the building and only one technician, someone who had been vetted by the ultra-secretive National Security Agency, could go inside. Although Klein had access to every other corner of the facility, neither he nor any other employee was allowed to enter the secure room — not even when an industrial air conditioner inside malfunctioned and water began leaking through the floor into the rooms below.

Several years later, Klein submitted a sworn declaration in a federal court that the NSA was provided with the room so it could monitor all the Internet traffic AT&T carried on its network. Civil libertarians contend that Klein’s declaration is a damning snapshot of an incalculably broad and inappropriate surveillance program that got under way just weeks after the Sept. 11 attacks — and continues to benefit from an unprecedented level of telecommunications industry cooperation.

Almost all the details about the NSA’s spying on phone calls, email and Web searches remain highly classified and closely held. But, according to its critics, the surveillance dragnet on electronic communications has been cast wide for nearly a decade — using a legal rationale established by the Bush administration that can be described as shaky at best. (It was shaky enough that in 2004, Attorney General John Ashcroft, FBI Director Robert Mueller and other top federal law enforcement officials were prepared to resign unless the surveillance program was changed.)

Critics say the phone companies have wrongly allowed themselves to be conscripted into the effort. Giving the government access to the main veins ferrying commerce and conversation has caused the already-dwindling notion of personal privacy to dissolve even faster, they lament, and has also fundamentally weakened the legal principle that people who aren’t suspected of wrongdoing should be left alone by the police.

But the industry, while extremely reluctant to detail its cooperation, clearly had every patriotic incentive (at least initially) to do whatever the government said was reasonable to help in the hunt for terrorists. And the companies have had a business imperative for continued cooperation, as well: Any of their reputations, and their stock prices, could be damaged by revelations that a terrorist attack succeeded because one of the companies prevented the plotters’ phones from being tapped.

The Bush administration admitted only to conducting warrantless surveillance of electronic communications that involved at least one person outside the United States who was suspected of being involved in terrorism. But critics say there’s little doubt that the NSA monitors not only international communications, but also those in which both parties are in the United States.

A Two-Way Street

In the newly symbiotic relationship between the government and the telecommunications industry, the unusual assistance has flowed both ways. After the existence of at least part of the surveillance program was publicized by The New York Times in 2005, the government moved on multiple fronts to shield the phone companies from both public scrutiny and legal liability.

The Justice Department asserted the “state secrets privilege” on the companies’ behalf in lawsuits that civil libertarians filed alleging that the warrantless surveillance program broke multiple laws. And the department filed lawsuits of its own to block state officials from forcing the companies to turn over information about the program. Most importantly, the Bush administration engineered enactment of a 2008 law implementing an unusual retroactive legal immunity for the cooperating companies.

The government’s multipronged defense of the phone companies in Congress and the courts was necessary to save the companies millions of dollars. Under federal law, for example, each plaintiff could collect at least $10,000 — or $100 for every day of wrongful eavesdropping. If the NSA surveillance program really involved as many millions of customers as its critics suspect, the potential total in legal damages could have crippled the entire telecommunications sector.

The public has largely overlooked the sector’s cooperation with post-attack anti-terrorism efforts during the last decade, because much of it has remained secret, and nobody wants to live through another devastating terrorist attack.

A Longstanding Partnership

Government regulators have looked favorably on the telecommunications industry, too. The Justice Department and the Federal Communications Commission have approved four blockbuster mergers in the last 10 years, essentially recreating the old Bell System monopoly as a duopoly of AT&T and Verizon. The sector benefited from a host of other favorable regulatory decisions as well, such as the FCC’s move six years ago to classify broadband Internet service delivered over phone lines as an “information service,” essentially shielding it from the historically stringent regulations placed on telephone networks.

Even critics of that deregulatory trend hesitate to draw a direct connection to the industry’s cooperation with the NSA. But even if it is only a coincidence, industry consolidation has helped the spy agencies because they have fewer companies to deal with. The current landscape “certainly makes it easier to centralize control or garner a pretty widespread surveillance or monitoring regime,” said Sascha Meinrath, a telecommunications policy expert at the centrist New America Foundation think tank in Washington.

Telephone companies have always had a quietly cooperative relationship with law enforcement. The issue of wiretapping didn’t reach the Supreme Court until 1928 — about six decades after the phone was invented — and the justices ruled that the government could listen in at will without violating the Fourth Amendment’s prohibition against warrantless searches. After the court changed its mind in 1967, Congress wrote the first rules governing federal wiretapping power. The rules for obtaining warrants were tightened a decade later by the Foreign Intelligence Surveillance Act, written after a Senate panel known as the Church Committee unearthed decades of abuses by law enforcement and intelligence agencies.

But after the first reports of post-Sept. 11 warrantless wiretapping surfaced five years ago, there was no sustained congressional investigation into alleged wrongdoing — meaning the full extent of the surveillance, and the phone companies’ cooperation, could remain under wraps to this day. “It is a continuing frustration for us that, 10 years later, there hasn’t been full disclosure of what happened,” said Michelle Richardson of the American Civil Liberties Union.

After going on defense and rebuffing efforts by aggrieved citizens to get the details in court (by declaring that their explanations would have to disclose state secrets) Bush administration officials then went on offense by pushing to give telecommunications companies retroactive legal immunity for their cooperation — a tacit acknowledgment of the illegality of the program. Democrats pushed for limited immunity only, but in the end Congress relented to the president’s demand.

Once that law was enacted in 2008, many of the lawsuits against the phone companies started getting dismissed. But one civil liberties group, the Electronic Frontier Foundation, is trying to get the 9th U.S. Circuit Court of Appeals to rule that the three-year-old immunity provision is unconstitutional and that federal officials should be subject to civil liability for wrongful wiretapping. An oral argument in that second case is scheduled for the end of the month.

Congress will have a chance to revisit the surveillance issue next year, when provisions of the law are set to expire. In July, two Senate Democrats, Ron Wyden of Oregon and Mark Udall of Colorado, wrote to Director of National Intelligence James R. Clapper Jr. to pose several questions about how intelligence agencies are operating under the law. They also asked Clapper about another surveillance trend: the use of cell phone location data by law enforcement agencies to track individuals.

But there is little, if any, chance that lawmakers will do anything to disturb the extraordinary legal shield they placed over the telecommunications sector to insulate it from liability for cooperating with the NSA surveillance program, which Wyden calls a “very troubling precedent.”