My chat with director Laura Poitras started like so many other interviews do, with a simple request to record the conversation for accuracy in quoting. In journalism, the ethical norm of interviews is this: Ask for permission, and sources agree or they don’t.

Poitras quickly agreed when I spoke to her this week about her documentary portrait of controversial NSA whistle-blower Edward Snowden, CITIZENFOUR.

“At least I asked,” I said, joking.

Poitras responded with a polite chuckle, but as her latest work can attest, in terms no American can make light of, the National Security Administration has been considerably less ethical than I was—or any such agency in our country's history, for that matter—when it comes to gathering information about citizens and people around the world alike. Her voice, crumbly and quiet, narrates the tight chronology of the film, which opens with her reading letters that she exchanged with Snowden as she was trying to vet him as a source and closes in the aftermath of his revelations and life in exile.

"We knew this was an extraordinary portrait of someone at a point of no return, who made decisions that there’s no return from, without knowing what the future would hold," Poitras said.

"From the first awkward meeting to going into the documents to talk about programs, then Glenn [Greenwald] starts to publish and you feel the world start to close in on us, because it’s clear the government thinks he’s the source and there’s a limited amount of time before they might come forward with his name."

As the stories Poitras and fellow journalist Greenwald wrote were published last year, and her source became her documentary's subject, former NSA contractor Snowden revealed that the American government has a broad-reaching surveillance program that collects information on the electronic lives of Americans and watches the world. The revelations made global headlines and earned the Obama administration considerable backlash from other heads of state, including German Chancellor Angela Merkel after it was revealed her phone had been hacked.

Despite the many headlines, what we didn’t know until CITIZENFOUR’s release were the details of what revealing that truth meant for the now 31-year-old and how his life changed in the days since: big details, such as how his girlfriend noticed a sudden influx of suspicious cleaning trucks on their block, though she had no idea why she might be watched because he kept her in the dark to protect her, and small details, like his bad hair days. (CITIZENFOUR is being distributed theatrically by Radius, in association with Participant Media—TakePart's parent company—and HBO Documentary Films.)

One of the most significant challenges of the film, in the end, served to simply express the isolation of being a lone whistle-blower: Nearly an hour of the film was shot in the Hong Kong hotel that became Snowden's de facto home once his identity was revealed and before he was forced to take refuge in Moscow. The close look may change some people's notions of what sort of person he is, Poitras hopes.

"Clearly he’s motivated by a set of beliefs, and he’s making huge personal sacrifices," Poitras said. "Whether or not you agree in the end, that’s up to every individual viewer.... I do think it changes people’s attitude towards him, because if they think he was fame-seeking or all that kind of stuff, in the film there’s no evidence to support that."

Beyond humanizing Snowden in cinema verité, the big picture that is painted about American surveillance is what stays with you. For now, Snowden says there is too much information being gathered to even be useful to modern spycraft—but the groundwork is being laid for something much more ominous, and there is little to no oversight in post-9/11 America, where rules have loosened to allow more surveillance than many understand.

At its heart, it is a story about how he may have been one of the greatest secret sources in American history, and how he advanced a dialogue we didn't know this country should be having. Snowden and other whistle-blowers are pressing a slew of questions about government surveillance into the American consciousness: “Is this really the country that we want to be? Do we really want this government to have these powers of surveillance and for these decisions to be made in secret, and with secret interpretations of laws?” Poitras said.

But Snowden doesn’t just raise questions—he answers them, and Poitras reveals that he was a dream source for any journalist. In the film, Snowden is organized, well-spoken, and patient and seems to perfectly lack self-interest. Add to that his impressive technical knowledge, his patience in teaching journalists a complicated subject, and his selfless devotion to the truth. For any journalist who has dealt with a secret source, half the battle is figuring out how the source may be abusing the power of the press for self-serving reasons and weighing that against the value of the information being revealed.

"That’s, in a sense, that’s the bigger message about the film," Poitras said. "Yes, it’s about NSA surveillance, but it’s also about people willing to make personal sacrifices to say, 'This is what the government is doing, and it’s not OK that it’s happening in secret.' "

As CITIZENFOUR reveals, Snowden gave up everything—his job, his comfortable life in the U.S., his peace of mind—to leak the truth to Poitras and Greenwald.

As reward, Snowden has been publicly called a traitor by pundits and is wanted by federal justice officials for criminal charges of espionage for revealing America’s massive surveillance programs.

But when the history books are written to include Snowden, he may bear more comparison to another source who revealed unseemly truths about the abuse of American power: Deep Throat, the infamous source who helped Washington Post reporters break the Watergate scandal.

When asked about Deep Throat's motives in 1997, here's what legendary editor Ben Bradlee had to say:

“I think he had a strange, passionate devotion to the truth and a horror at what he saw going on.”

Viewers of CITIZENFOUR may agree that no less can be said of Snowden.