Klein's allegations and the news reports about them launched dozens of consumer lawsuits in early 2006 against the government and telecommunications companies. The lawsuits alleged invasion of privacy and targeted the very same provisions of the Foreign Intelligence Surveillance Act that are at the center of the latest public outcry.
That was seven years ago, and the warrantless collection continues, perhaps on an even greater scale, underscoring just how difficult the recently outraged will have in pursuing any new lawsuits, like the one the American Civil Liberties Union filed against the government on Tuesday in New York federal court.
"I warned whoever I could," Klein said in telephone interview from his home in Alameda, a city across the bay from San Francisco. "I was angry then. I'm angrier now."
All the lawsuits prompted by Klein's disclosures were bundled up and shipped to a single San Francisco federal judge to handle. Nearly all the cases were tossed out when Congress in 2008 granted the telecommunications retroactive immunity from legal challenges, a law the U.S. Supreme Court upheld. Congress' action will make it difficult to sue the companies caught up in the latest disclosures.
The only lawsuit left from that bundle is one aimed directly at the government. And that case has been tied up in litigation over the U.S. Justice Department's insistence that airing the case in court would jeopardize national security.
"The United States government under both administrations has been stonewalling us in court," said Lee Tien, an attorney with the Electronic Frontier Foundation, which represents the consumers who filed that lawsuit. EFF has also filed a related lawsuit seeking the Justice Department's legal interpretation of the law that the government is apparently relying on to collect consumers' electronic data without a warrant.
James Clapper, director of national intelligence, personally urged U.S. District Judge Jeffrey White to throw out the remaining lawsuit. Clapper wrote the judge in September that the government risks "exceptionally grave damage to the national security of the United States" if forced to fight the lawsuit.
But on Friday, federal prosecutors asked the judge to delay making any decision until it can report back to the court on July 12 what the latest disclosures may mean to the lawsuit. Tien and other EFF lawyers are also assessing the newest disclosures to determine if they bolster their case.
Snowden, 29, a former CIA employee who most recently worked as a contractor for the National Security Agency, admitted leaking details of two secret government surveillance programs.
He revealed a top-secret court order issued April 25 by the Foreign Intelligence Surveillance Court that granted a three-month renewal for the large-scale collection of American phone records. That program, the same one Klein tried to expose, allows the NSA to gather hundreds of millions of U.S. phone records to search for possible links to terrorists abroad.
Snowden also disclosed another program that allows the government to tap into nine U.S. Internet companies and gather all communications to detect suspicious behavior that begins overseas.
On Tuesday, Klein said that for a number of reasons, Snowden's disclosures sparked more public outrage than his own revelations did more than seven years ago.
For one thing, Klein said, Snowden had direct access to a secret court order and details of the program, while Klein pieced together the government's surveillance through internal AT&T documents and in discussions with colleagues who worked on the project.
"The government painted me as a nobody, a technician who was merely speculating," said Klein, who made his disclosures after he accepted a buyout and retired from AT&T in 2004. "Now we have an actual copy of a FISA court order. There it is in black and white. It's undisputable. They can't deny that."
Klein also said the allegations that the government was accessing social media sites such as Facebook may have gotten the attention of more — and younger — people who weren't bothered by his initial disclosures.
"Now, the government is intruding in places they go," said Klein, 68. "That probably got their attention."