Companies and government agencies increasingly moved information to remote cloud servers, maintained in many cases by the same companies that documents showed were working with the NSA to gather information. (Connie Zhou/AP)

Expanded government surveillance was cast as a price of war in the aftermath of the Sept. 11, 2001, attacks. Yet nearly a dozen years later, the war on terrorism is showing signs of ebbing while the surveillance systems created to fight it continue unabated.

If anything, they are becoming more powerful.

That’s because the nation went to a war footing at a time of profound technological change that fueled an explosion of personal data. Governments and businesses have developed the ability to mine, sort and analyze this information as never before — and show little inclination to relinquish that power.

Few adults can navigate the modern world without leaving behind massive trails of data: where we go, where we live, how we look, what we buy, what we eat, what Web sites we visit and — perhaps most powerfully for those seeking to monitor us — who is in our network of personal relationships.

From a legal perspective, this information is considered fair game in our wired world, given freely with every e-mail sent, every photo posted to Facebook, every bag of groceries bought with a credit card. Yet few people knew that much of this information could be vacuumed up by the National Security Agency, in partnerships with many of the nation’s most prominent technology companies, for possible use in broadly defined terrorism investigations.

“What the government can do is certainly much greater than before 9/11,” said Daniel Solove, a George Washington University law professor and author of “Nothing to Hide.” “The Obama administration by and large has not done anything to dial it back. If anything, maybe they’ve dialed it forward.”

Slow legal evolution

President Obama forcefully defended the program Friday, arguing that it involved safeguards against unwarranted surveillance of U.S. citizens and others in the country, and that it struck an appropriate balance between security and privacy concerns. Documents showed that information gathered through the secret NSA program, PRISM, was a major source of intelligence information delivered to the president in his daily briefing each day.

Yet details of PRISM, revealed in reports this week by The Washington Post and the Guardian citing government documents, startled even some veteran civil libertarians who had long warned about growing government surveillance powers but didn’t expect them to be so vast.

“The fact that there would be so much data collected on U.S. persons has got to be mind-blowing,” said Marc Rotenberg, president of the Electronic Privacy Information Center. “The sense we have now is that the system of checks and balances has simply collapsed.”

Snooping is as old as communication itself, and with each technological advance, authorities have pressed for surreptitious access. That was straightforward in the days when police could tap directly into telephone wires but grew increasingly complex with the arrival of e-mail, cellphones, and encrypted voice and video services such as Skype.

The legal guidelines for government interception of communications have evolved more slowly, with many crucial laws and precedents dating to the days when rotary phones were still common. Especially crucial was a Supreme Court decision in 1976 upholding the “third-party doctrine” — meaning that anyone turning over information to a third party, such as a bank or Internet service provider, has no right to object if that information is later shared with the government.

That is the legal key that has unlocked the government’s access to massive amounts of personal information, giving it justification to tap into the servers of Google, Microsoft, Facebook, Apple, AOL and four other technology companies, according to an NSA presentation obtained by The Post. (Several of the companies denied that the NSA had any direct access to their servers.)

Government officials pushed for more access to data in the urgent aftermath of the Sept. 11 attacks — over the objections of civil libertarians who argued that security concerns should be more evenly balanced with personal freedoms, even at a time of war.

Backlash to overreach

There has been some backlash to government overreach, as there was amid revelations about the Bush administration’s warrantless wiretapping and the Pentagon’s “Total Information Awareness” program, which sought to monitor terrorist activity but was criticized as an unnecessarily intrusive surveillance effort.

The same criticism was leveled this week at the NSA surveillance program. Although approved by a secret Foreign Intelligence Surveillance Court, some legal experts said the effort could have violated the law and perhaps the constitution’s prohibition on unreasonable searches and seizures. Written at a time when memories were fresh of the British barging into the private homes of colonists and seizing whatever they wanted, the Fourth Amendment requires probable cause and specific investigatory targets.

“You’ve completely undermined the purpose of the Fourth Amendment,” said Laura Donohue, a Georgetown law professor.

Yet since the Sept. 11 attacks, the government has won most of its political battles over powers it says are necessary to fight terrorism. The widening legal authorities came as computing power surged. Social media services, such as Facebook, became wildly popular. And many Americans began using smartphones, capable of emitting a constant stream of information about their owners.

Companies and government agencies, meanwhile, increasingly moved information to remote cloud servers, maintained in many cases by the same companies that documents showed were working with the NSA to gather information.

“The rat-tat-tat of repeated government and business blowups over privacy are going to increase the sense of edge that some consumers have today about the sharing of information,” said Jules Polonetsky, a former AOL privacy official and director of the Future of Privacy Forum, an industry-supported think tank.

Yet so far, there has often been public resignation to eroding privacy, some advocates say. Outrage over changes to Facebook privacy settings, or to Google’s scooping up of user data through its Street View program, has generally subsided not long after the initial publicity.

Wall Street is betting that there will be little price to pay for participating in the NSA program. On Friday, the first day after the news reports, not one of the technology companies involved saw its stock price drop.

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