The filmmaker Laura Poitras is concerned with the human effects of surveillance. She wants to understand what pervasive and sometimes aggressive American intelligence gathering does to people. And she wants to understand the human beings who have created it, run it, and become disillusioned by it -- men who now find themselves at war with the system. In her new film, Citizenfour, we get unprecedentedly close to the human source -- Edward Snowden -- of revelations that have rewritten the way that large parts of the world understand the nature of American intelligence, surveillance, and power. 
 
 And then Poitras pulls us back. 
 
 Poitras, a journalist and documentary filmmaker, is one of the foremost chroniclers of the U.S. war on terror, and Citizenfour is the third in a trilogy of movies examining the human costs of that conflict. (Its title refers to Snowden's moniker when he first contacted Poitras.) Poitras now lives in Berlin, where she is part of a growing expat community working on digital privacy issues. Together with Glenn Greenwald, the Guardian journalist, she serves as the primary conduit for Snowden leaks. 
 
 It bears saying that the former NSA contractor indicted in the United States under the Espionage Act chose Poitras, whose work he admired -- particularly her short video for the New York Times -- and knew she had some facility with technical encryption. As someone who has written about Snowden since he first appeared in the summer of 2013, I think the choice of Poitras as an interlocutor was the best of all his wildly successful gambits. Snowden and Poitras first had contact with one another in January 2013; it can be easy to forget how incredible it is that they weren't caught by the NSA. That's a technical feat for which Poitras deserves much of the credit. 
 
 Citizenfour is the most complete account of how their relationship developed. It is a story of great daring, one that dabbles in a conspiracy theorist's paranoia and indeed provides a more human portrayal of Snowden. It is not a neutral film in the old-fashioned, journalistic sense of the word -- and that's not a bad thing. 
 
 It can be divided into three parts: before Snowden, with Snowden, and after Snowden. B.S. features Bill Binney -- the legendary NSA crypto-mathematician turned whistleblower -- and Greenwald, who argues about civil liberties from his home in Brazil. It also features the Internet activist and hacker Jacob Appelbaum, one of the film's more interesting characters, teaching left-wing activists about electronic surveillance. 
 
 Then Snowden appears, much like a bolt of lightning. And with his arrival, Poitras must negotiate her role as a character in her own film. This is a very serious problem for Poitras, for whom appearing in her own work is anathema. Poitras is deeply aware of the observational problem of documentary filmmaking, of the way that the camera's presence alters the reality or truth being filmed. It's a conundrum with an analog in quantum mechanics: The measurement problem. 
 
 That she has authored multiple, award-winning articles based on Snowden-provided material further complicates Poitras's entanglement with Snowden. Snowden, then, is someone whom she has to protect as a source and expose as a subject. That's something of a filmic quandary. 
 
 Poitras's solution is acting as a semi-passive observer, having the camera at her hip, not blocking her face. "The camera doesn't have to be a barrier," she told the New Yorker. "It's a witness." In Citizenfour, she appears most as a disembodied voice, reading eerie messages she received from Snowden via encrypted channels. 
 
 By my count, Poitras makes one visual appearance in the film: When Greenwald and Poitras first meet Snowden in a Hong Kong hotel, she is caught briefly in a mirror reflection. That moment comes just as the audience meets the source, Snowden, for the first time. He sits on a bed, disheveled, a little dazed, and obviously nervous. The effect is like a shock of the new: This thing that we thought we knew completely presented at a moment just prior to his (public) birth. He has no idea what's coming. It's an incredible piece of footage, which also captures the intimacy of Poitras's cinematic technique. 
 
 The movie's high point comes when it's just Poitras and her subject in a hotel room. A talking head on BBC argues in the background that Snowden could have been pulled out of a book by the spy novelist John le Carré. Snowden walks around the room in a black suit jacket and black pants. He tries to get his hair to stay in place with some gel. It doesn't go well. He holds up a green umbrella before a mirror, considering his disguise for escaping the hotel. Too much, he decides. It's a lovingly shot scene. Poitras sees Snowden as a human being. For a moment it's not Snowden "the leaker," Snowden "the whistleblower," Snowden "the traitor." Instead, just a goofy guy, one far removed from the world of le Carré. 
 
 And then, just as abruptly as he arrived, Snowden goes underground to seek asylum and, eventually, with the help of WikiLeaks, lands in Moscow. With the protagonist gone, the film sags a bit. Snowden reappears via encrypted chat. But he is distant, more removed. Greenwald moves to the forefront. His testimony to Brazilian lawmakers on U.S. surveillance is of a different register than the poetic footage from Hong Kong. One lives again the drama of the Snowden revelations as they played out on cable television. It's less riveting footage than meditations on Snowden's psyche in Hong Kong's neon dreamscape. 
 
 Perhaps as a result, the portrait of Snowden ends up feeling incomplete. The film ends back in Moscow -- after Snowden has secured asylum and the aftermath of his revelations has been documented on screen -- with a meeting between Snowden and Greenwald, who reveals that he has acquired a new source high up in the U.S. intelligence bureaucracy. And so it becomes a film with an easy moral message: Snowden did this for pure purposes at immense risk to himself, and it has resulted in more like him stepping forward. That may very well be true, but it's so unmessy that it's almost unbelievable. 
 
 The more complicated aspects of Snowden's personality come as a footnote. We get a brief shot, filmed with a long lens so it feels like they are surveilled, of Snowden and his girlfriend, Lindsay Mills, cooking dinner together. That Mills traveled to Moscow to be with Snowden is the film's only real revelation, but she never appears in the movie as a subject. Mills was reportedly willing to go on camera but Poitras turned her down out of an apparent desire to keep the film focused on Snowden and, one senses, the "issues." When Snowden appears in Hong Kong chatting with his girlfriend on his laptop, Poitras retreats. We don't know what they say to one another. 
 
 Therein lies the point at which Poitras retreats from her subject, perhaps to protect him. And, sure, it would be invasive to ask Snowden to tell us what he's typing out to his girlfriend. But these are the conundrums of trying to establish interiority in a documentary film. And given Poitras's humanistic commitments, it's surprising that she didn't explore this relationship further. 
 
 Perhaps more surprising is her unwillingness to more directly confront a bigger question hanging over Snowden: whether the use of illiberal means can ever be justified as a defense of the liberal state. Unmentioned in the film are the Chinese and Russian intelligence services, which move through its background. These organizations have similar, if not as expansive, capabilities as their counterparts in the United States, to say nothing of their ability to imprison political opponents and use physical violence against detainees with impunity. And some of Snowden's revelations did not just deal with the gathering of intelligence against Americans but also with operations against countries such as Iran and Pakistan, both of which have deplorable human rights records and sponsor or condone violence outside their own borders. 
 
 And therein lie the questions about Snowden that Poitras -- perhaps too close to the man -- cannot answer. Snowden, as he was presented to the public, remains so uncomplicated that he feels flat. Some of America's intelligence work is indeed deplorable, but so are the intelligence operations of other countries. What the film lacks is how Snowden grappled with the question of how one deplorable thing differs from another. 
 
 And in the absence of a more rounded portrait of him, conspiracies flourish. Circumstantial arguments are made about how he is a Russian agent and was recruited long ago. The wild theories don't quite add up -- which is in part why they thrive -- but his defenders don't have a lot of material at their disposal to rebut them either. 
 
 Bryan Bedder/Getty Images for The New Yorker ||||| Two reporters for The Guardian were in town to assist Greenwald, so some of our time was spent in the hotel where they were staying along Copacabana Beach, the toned Brazilians playing volleyball in the sand below lending the whole thing an added layer of surreality. Poitras has shared the byline on some of Greenwald’s articles, but for the most part she has preferred to stay in the background, letting him do the writing and talking. As a result, Greenwald is the one hailed as either a fearless defender of individual rights or a nefarious traitor, depending on your perspective. “I keep calling her the Keyser Soze of the story, because she’s at once completely invisible and yet ubiquitous,” Greenwald said, referring to the character in “The Usual Suspects” played by Kevin Spacey, a mastermind masquerading as a nobody. “She’s been at the center of all of this, and yet no one knows anything about her.” 
 
 As dusk fell one evening, I followed Poitras and Greenwald to the newsroom of O Globo, one of the largest newspapers in Brazil. Greenwald had just published an article there detailing how the N.S.A. was spying on Brazilian phone calls and e-mails. The article caused a huge scandal in Brazil, as similar articles have done in other countries around the world, and Greenwald was a celebrity in the newsroom. The editor in chief pumped his hand and asked him to write a regular column; reporters took souvenir pictures with their cellphones. Poitras filmed some of this, then put her camera down and looked on. I noted that nobody was paying attention to her, that all eyes were on Greenwald, and she smiled. “That’s right,” she said. “That’s perfect.” 
 
 Poitras seems to work at blending in, a function more of strategy than of shyness. She can actually be remarkably forceful when it comes to managing information. During a conversation in which I began to ask her a few questions about her personal life, she remarked, “This is like visiting the dentist.” The thumbnail portrait is this: She was raised in a well-off family outside Boston, and after high school, she moved to San Francisco to work as a chef in upscale restaurants. She also took classes at the San Francisco Art Institute, where she studied under the experimental filmmaker Ernie Gehr. In 1992, she moved to New York and began to make her way in the film world, while also enrolling in graduate classes in social and political theory at the New School. Since then she has made five films, most recently “The Oath,” about the Guantánamo prisoner Salim Hamdan and his brother-in-law back in Yemen, and has been the recipient of a Peabody Award and a MacArthur award. 
 
 On Sept. 11, 2001, Poitras was on the Upper West Side of Manhattan when the towers were attacked. Like most New Yorkers, in the weeks that followed she was swept up in both mourning and a feeling of unity. It was a moment, she said, when “people could have done anything, in a positive sense.” When that moment led to the pre-emptive invasion of Iraq, she felt that her country had lost its way. “We always wonder how countries can veer off course,” she said. “How do people let it happen, how do people sit by during this slipping of boundaries?” Poitras had no experience in conflict zones, but in June 2004, she went to Iraq and began documenting the occupation. 
 
 Shortly after arriving in Baghdad, she received permission to go to Abu Ghraib prison to film a visit by members of Baghdad’s City Council. This was just a few months after photos were published of American soldiers abusing prisoners there. A prominent Sunni doctor was part of the visiting delegation, and Poitras shot a remarkable scene of his interaction with prisoners there, shouting that they were locked up for no good reason. 
 
 The doctor, Riyadh al-Adhadh, invited Poitras to his clinic and later allowed her to report on his life in Baghdad. Her documentary, “My Country, My Country,” is centered on his family’s travails — the shootings and blackouts in their neighborhood, the kidnapping of a nephew. The film premiered in early 2006 and received widespread acclaim, including an Oscar nomination for best documentary. 
 
 Attempting to tell the story of the war’s effect on Iraqi citizens made Poitras the target of serious — and apparently false — accusations. On Nov. 19, 2004, Iraqi troops, supported by American forces, raided a mosque in the doctor’s neighborhood of Adhamiya, killing several people inside. The next day, the neighborhood erupted in violence. Poitras was with the doctor’s family, and occasionally they would go to the roof of the home to get a sense of what was going on. On one of those rooftop visits, she was seen by soldiers from an Oregon National Guard battalion. Shortly after, a group of insurgents launched an attack that killed one of the Americans. Some soldiers speculated that Poitras was on the roof because she had advance notice of the attack and wanted to film it. Their battalion commander, Lt. Col. Daniel Hendrickson, retired, told me last month that he filed a report about her to brigade headquarters.
– Those following the Edward Snowden case will probably recognize the name Glenn Greenwald as the journalist writing up all the resulting scoops. But Laura Poitras? She's a 49-year-old documentary filmmaker from the US who is working with Greenwald and is crucial to the Snowden saga, reports Peter Maass in a fascinating New York Times Magazine piece. Greenwald himself sums it up with a reference to the Kevin Spacey flick the Usual Suspects: “I keep calling her the Keyser Soze of the story, because she’s at once completely invisible and yet ubiquitous. She’s been at the center of all of this, and yet no one knows anything about her.” Turns out that Greenwald initially ignored Snowden's "annoying and complicated" emails, prompting Snowden to turn to Poitras. He knew she was making a documentary about surveillance, and she used her expertise in encryption technology to begin a dialogue with him—and eventually sell Greenwald on the story. If the name rings a bell, it's because Poitras has made a number of controversial documentaries about Iraq and Abu Ghraib, earning herself a spot on a US watch list and thus dozens of airport interrogations. (Greenwald wrote about her travails in Salon.) The full Times piece details their first meetings with Snowden (they were shocked at how young he was) and the resulting chaos when the first stories appeared. “Our lives will never be the same,” says Poitras. “I don’t know if I’ll ever be able to live someplace and feel like I have my privacy. That might be just completely gone.” Read the full story here.