Vienna-based documentary maker Friedrich Moser has long been interested in the business of surveillance. But even he was taken aback when he heard a U.S. whistle blower and former National Security Agency insider tell him how the 9/11 terrorist attacks could have been prevented.

William Binney had travelled to Austria in 2014 for a film that Moser planned to make about how western governments' intelligence priorities had changed. In particular, Moser wanted to explore why governments were so keen to spy on the public in the post-9/11 period.

"How did we actually come from the scenario of the Cold War when the intelligence agencies had been surveilling our military enemy to a situation where we, the citizens, have become the enemies?" Moser told the Georgia Straight by phone from Vienna. "Because now, they were surveilling us."

Binney had a 30-year career doing intelligence work, so Moser felt that he would be an ideal character through which to tell this story.

But when Binney arrived in Vienna in October 2014 for background discussions for the documentary A Good American, he revealed a more surprising tale.

The former intelligence analyst explained that the NSA had a project called ThinThread in the 1990s. It involved wiretapping, which was followed up by extensive analysis of the data that was collected.

A central element of ThinThread was looking at who was communicating with whom to understand the command structure of terrorist networks.

At the same time, Binney maintained to Moser that it included built-in protections to maintain the rule of law by requiring warrants to gather the contents of phone conversations.

Real-time analysis could be performed on the metadata by screening out most of the chatter over the Internet and phone networks in advance and focusing more attention on connections between callers.

"You have to do a filtering up front that eliminates something like 99.5 percent of the traffic," Moser explained.

This enables analysts to learn of the existence of conversations as close as possible them occurring. In turn, that can quicken preventive measures to disrupt plots.

However, the director of the National Security Agency at the time, Michael Hayden, chose to go with a different project known as Trailblazer, which was advanced by a private-sector consortium. It didn't include the same degree of screening and instead vacuumed up everything without any filtering.

This not only undermined Americans' civil liberties, but it was also less efficient, according to the film.

In A Good American, Binney reveals that when he and other analysts went back and reviewed intelligence records after 9/11 using ThinThread. And shockingly, he claims that it would have revealed the 9/11 plot in advance.

Moser said that he was "blown away" by this revelation.

"This was the first time I heard the story of ThinThread," he said "My jaw dropped because I thought it's probably the most amazing story I had heard in my life."

A Good American makes a strong case that without filtering of incoming data, it became impossible to conduct the proper analysis in real time, giving the 9/11 plotters more time to succeed.

But the contracting out of intelligence work has proven to be a gold mine for the private sector. According to Moser, the 16 U.S. intelligence agencies spend about $100 billion per year.

"This is largely a story about money," he said. "I mean, that's capitalism. At the root of all that, I think, is outsourcing."

The filmmaker maintained that the ultimate goal of any private company is generating profits. And this, he suggested, is more important than civil liberties, maintaining national security, or even conforming to the law.

"That's a natural consequence," Moser said. "So the kind of debate we should have is when does the public start and the private end. Where is the line that we have to draw?"

In answering his own question, he expressed the belief that the government doesn't need to own steel mills. Then he added that "being in charge of the police and being in charge of national security is a really elementary task of the state".

"It should not be privatized," he added. "Not at all. Because the kind of thing we're going to end up with is warlords...and a mercenary police."

Moser said that the proponents of outsourcing, including Hayden, did not make themselves available to tell their side of the story, despite the filmmaker's efforts to reach them.

While Binney is the star of the movie, there's a cast of other whistle blowers who speak to his prowess as an outstanding intelligence analyst. They include former NSA workers Kirk Wiebe and Ed Loomis, as well as Diane Roark, who was a budget expert with the House intelligence committee.

Moser said it wasn't an easy film to make because there were no photographs or usable film footage of Binney on the job as a security analyst. To address this, the director had Binney re-create tasks, like looking through filing cabinets, breaking codes on paper, and looking at old photos.

Interviews are often conducted with dark backgrounds. Binney is seen playing chess or going out on his back porch in the evening. It creates a mood of what it's like working as super-secret intelligence analyst. The musical score adds a sinister feel.

"I thought okay, if this is a real-life thriller, why not give it the feel of a thriller? Moser said. "This is what I was going for."