(Photo: Sean Gallup/Getty Images)

"Fallon" is not her real name. It's a pseudonym she's using because she wants to remain anonymous. She knows that can be an elusive goal, chiefly because of people not unlike her.

When I first contacted Fallon, here is what she told me about herself: she's in her mid-30s; she's white; she has children; she works a nine-to-five office job; and she lives in Ohio. She has a voice like a school teacher or a nurse, steady and determined. She loves PowerPoint slides and spreadsheets. She seems organized, efficient, and articulate.

She also says she is part of Great Lakes Antifa, a self-described group of anti-fascist activists. Within her local antifa group, she says she is part of an even smaller collective. These are what are known as the antifa "doxxers." In the evenings and her spare time, Fallon says she researches and reveals the identities of neo-Nazis in America.

Often beginning with nothing more than a name, or even a picture, Fallon says she tracks down people who have attended far-right rallies or meetings, who have sent death or rape threats on the Internet, or who are members of white supremacist groups like the KKK or National Socialist Movement. She says she uses property records, tax documents, voter registration databases, social media, real estate websites, and real-life surveillance to find them and verify their names and locations.

And then she makes a choice. What kind of dox will she do?

For some of her targets, she says she contacts their church or employer, emailing screenshots of the online abuse they allegedly have perpetrated. For others, she calls their workplaces or colleges to explain that an employee or student says they are a member of a white supremacist group. And in the most serious cases, she says, she publishes their names on sympathetic left-wing news sites, like It's Going Down. As a result, people aligned with antifa might make posters naming and identifying the individual as a threat, putting them up around the person's town or community.

While Fallon's doxxes may have serious consequences, her work is relatively mild compared to some other doxxing cases. In some high-profile instances, doxxing has involved publishing a person's home address and then actively encouraging people to harass them. In one recent case, Tanya Gersh, a Jewish resident of white nationalist leader Richard Spencer's hometown Whitefish, Montana, was relentlessly harassed and threatened with phone calls after being named in a blog post on the neo-Nazi website The Daily Stormer. Andrew Anglin, the editor of The Daily Stormer, posted not only Gersh's phone number and address, but details about her 12-year-old son, and encouraged readers to harass them.

Fallon says she doesn't go this far. But she still believes her work is powerful.

"A dox is a digital brick through a window," she says.

The digital battle that Fallon is engaged in is just one form of combat between elements of the political left and right that has raged throughout 2017. In August, the potential for physical violence burst into the mainstream consciousness when white nationalists clashed with counter-protesters in the streets of Charlottesville, Virginia. The displays of far-right extremism, sometimes called the "alt-right," have occasionally been met with an anti-fascist opposition ready to use extreme methods, including violence, to push back. Such antifa members wound up in the clashes in Charlottesville.

For many Americans, the left/right warring—complete with competing manifestos and symbols and coded language—looks like little more than fringe nuttiness. But the street fights—whether in Berkeley, California, or Charlottesville—are quite real. The online sparring is less visible, but no less important to those caught up in the tumult.

Fallon and other antifa doxxers say they don't want to let people live secret lives of hate and bigotry. Their opponents on the right are not averse to online tussling either. Recent leaks from inside a white nationalist chat room showed the so-called alt-right planning to dox "anti-fascists" in retaliation for perceived humiliations in Charlottesville.

Doxxing exists in something of a legal gray area. The digital tools doxxers use and the public information they collect have long been used by journalists to investigate and write about people they've deemed newsworthy.

Fallon says she doesn't see her work as very different. She compares releasing the names of neo-Nazis publicly to the registering of sex offenders; while information about sex offenders is made public by government officials, Fallon notes the information is meant to help communities protect themselves. Fallon says she wants fascists out in the open.

"Sunlight cleanses. It sanitizes, it sterilizes," Fallon says.

Not everyone agrees. In "Cyber Misbehavior," a bulletin published by the Department of Justice in May of 2016, Assistant United States Attorney Joey Blanch and Executive Assistant Attorney Wesley Hsu, at the U.S. Attorney's Office Central District of California, described doxxing as a form of "cyberharassment."

"[Doxing] can expose the victim to an anonymous mob of countless harassers, calling their phones, sending them email, and even appearing at the victim's home," write Blanch and Hsu. However, as they point out, "There is no general reference to 'cyberharassment' under federal law."

It would be hard to introduce a single federal law against doxxing, says Danielle Citron, a law professor at the University of Maryland and author of Hate Crimes in Cyberspace, because it runs the risk of conflicting with the First Amendment. She points out that, while there are various state and federal laws in place to combat stalking, harassment, and clear threats, these don't always apply when someone's name, address, or phone number is published online. That information, after all, can be already available in the White Pages.

However, Citron still thinks any kind of doxxing is dangerous. "I don't care if it's neo-Nazis or antifa," she says, "this is a very bad strategy leading to a downward spiral of depravity." Citron's worry is that, all too often, doxxing ends up hurting the most vulnerable. "It provides a permission structure to go outside the law and punish each other," she says. “It’s like shaming in cyber-mobs."

The challenge of prosecuting cyber harassment is familiar to Ari Waldman, associate professor of law at New York Law School. He says creative lawyers are finding ways to help victims of doxxing, but they face challenges.

"Even where tools exist, where doxxing is part of a constellation of behaviors that constitute harassment, there are many instances where they won't win a lawsuit because online harassment is not taken seriously," Waldman says. Judges and juries frequently feel that, unless something physically threatening has happened, the publication of one's personal information is not, in itself, illegal.

Echoing Citron, Waldman worries that, if doxxing of the kind Fallon does becomes normalized, it risks legitimizing a dangerous tactic. "We need to be concerned about the use of this tool as a weapon," he says, "which usually affects marginalized populations."

I came into contact with Fallon while interviewing a string of other antifa activists about doxxing. One man cryptically mentioned a group of antifa doxxers renowned for their work. Would any of them speak to me, I asked?

A couple of days later, I got a polite email asking if I was interested in "learning more about digital doxxing of white supremacists," signed, "Warmest regards, Anonymous member of Great Lakes Antifa." Later, after we spoke on the phone, the woman gave me her nom de guerre: Fallon.

Fallon says she has rules. She says she never doxxes minors and rarely doxxes people of color. She sees a distinction between hardened members of far-right militias and a 19-year-old Donald Trump supporter flirting with white nationalist ideas. But she says she has no qualms about the final step of her research: outing those sympathetic to racist, white supremacist or fascist ideas.

"There's nothing more ethical than doxxing Nazis," she tells me.

Not only is Fallon a doxxer, she tells me she trains other anti-fascists and activists to dox, and to protect themselves from being doxxed. She says she's given her online webinar training to local liberal groups, as well as to anti-fascists across the country. In total, she claims she's run 25 webinars since November of 2016, training around 300 people.

Fallon agrees to walk me through the training she gives. Late one evening she texts me a website address via Signal, an encrypted messaging app. It links to a conference call program hosted on gotomeeting.com, a platform usually favored by businesses. At a prearranged time, I log in and find Fallon already on the line.

The workshop has the bland title "IT Security Training," but really it's split into two parts: learning to doxx, and learning how to protect yourself from being doxxed. "If you can dox it's easier to protect yourself from a dox," Fallon says. The first slide shows an agenda, with a picture of a man wearing black, his face covered, sitting at a computer.

The first point on the agenda is, "What is doxxing?"

Doxxing, Fallon explains, is the process of "gaining personal identifying information of a user, and using the information to socially engineer consequences." The word itself was coined by hackers in the '90s, from the phrase "dropping documents" or "docs," meaning to reveal someone's identity and information online.

She offers a brief history of doxxing, focusing on "Gamergate," a 2014 online controversy that resulted in various female video game designers and critics being doxxed and brutally abused on the Internet. Loosely organized through forums like 4chan and Reddit, Gamergate trolls targeted game developer Zoe Quinn and female journalists and gamers who spoke out to support her. Quinn fled her home, fearing she could be physically attacked by people who found her information online. She recently launched Crash Override, an advocacy group for victims of digital abuse. Three years later, she still receives threats.

For Fallon, the Gamergate episode was a watershed moment. "This was the first time the alt-right really coalesced," she says.

The doxxing Fallon says she does is nowhere near equivalent to that of the Gamergate trolls. As well as publishing the personal information of women they disagreed with, Gamergaters also sent death and rape threats, encouraging their targets to commit suicide.

Nonetheless, doxxing has become a major weapon for the left as well as the right.

In one sense, doxxing isn't particularly new. Anti-fascists have used the tactic of publishing information about fascists and hate groups for years. Groups like the Southern Poverty Law Center collect information and publish dossiers. The real difference now is the Internet, and social media in particular.

After the Unite the Right rally in Charlottesville, high-profile Twitter user and journalist Shaun King posted videos and pictures of so-called alt-righters committing acts of violence, and used crowdsourcing to identify information about the men. Some of these tweets led to arrests. The same tactic was used by the Twitter account, @YesYoureRacist, run by Logan Smith. These efforts also led to some serious misidentifications. One Charlottesville protester wearing an Arkansas engineering shirt was misidentified as Kyle Quinn, an engineering assistant. Quinn spent a weekend in hiding due to the amount of online abuse he subsequently received. The real protester, a former engineering student named Andrew M. Dodson, later apologized.

Unlike these Twitter vigilantes, antifa doxxers like Fallon don't do their work in public.

"The majority of our chapters," she says, "they're pretty ethical about what they do." She acknowledges that not every antifa doxxer might be as careful as she claims she is, and that sometimes mistakes have been made. "But those are getting fewer and fewer and farther between."

These tools are also being used by the far-right. Since antifa appearances in Berkeley and Charlottesville turned violent, so-called alt-right activists on social media and sites like Discord, 4chan, and 8chan have been trying to dox antifa members. More often than not, Fallon says, they fail, and end up doxxing "hapless liberals" instead, a trend confirmed by Keegan Hankes, an analyst at the Southern Poverty Law Center and Alexander Reid Ross, a scholar of the far-right and author of Against the Fascist Creep.

In May, a user called kanuke7 posted identifying information about thousands of signatories of a public anti-Trump petition on a pro-Trump Discord server, branding the signatories as "antifa." But Fallon says she has only ever seen a real antifa member doxxed by the right if they were first arrested and their identities made public by the police.

A risk Fallon doesn't mention here is that factions on both the left and right also sometimes use doxxing against each other as a weapon in internal disputes.

In a number of high-profile cases, antifa and other left-wing activists have significantly disrupted the lives of their doxxing targets. In the aftermath of the Unite the Right rally in Charlottesville, some participants reportedly lost their jobs, and one reportedly was even publicly disowned by his family.

Eli Mosley, leader of the white nationalist group Identity Evropa, recently expressed sympathy with those on his side whose identities have been made public.

"We deeply empathize with the various Alt-Right activists who have had their lives significantly affected over the past month," Mosley wrote in an article on AltRight.com. He issued a hard-line ultimatum to other white nationalists. "When faced with the crucible of doxxing and the subsequent employment and familial issues, an activist has two choices: double-down, or cuck. Everyone in our movement must be prepared to stand tall and double-down."

Ironically, as Keegan Hankes, an analyst at the Southern Poverty Law Center, says, when white nationalists are doxxed, it can get harder to keep track of them. Hankes has spent the last couple of years tracking far-right groups online. After Charlottesville, he says, so many people were doxxed and then kicked off social media platforms like Twitter and Discord, that his job became more difficult. He says so-called alt-right leaders were well aware in the run-up to Charlottesville that they were taking a risk.

"The message coming down from the top was, essentially, don't go to this event if you're not comfortable with the idea of being doxxed," Hankes says. "No matter what kind of bravado they put forward on their platforms, they know that many of their supporters are not known." They have reputations and jobs to protect, he says.

Sometimes banning hate speech from social media platforms does effectively reduce hate speech. In 2015, Reddit began banning subreddits that promoted harassment against specific groups. Using complex search algorithms for specific hate speech, Reddit aggressively moderated subreddits like /Coontown and /fatpeoplehate. After this crackdown, they found that, overall, offensive language decreased, while users determined to continue posting hate moved elsewhere.

Fallon searches for these hardcore users. She says the key to doxxing is social media, and the information people willingly reveal about themselves online. In her training session, Fallon points out that companies like Facebook and Twitter are multibillion-dollar corporations with high levels of security. She says antifa doxxers aren't hackers like Anonymous, and rely on something much more mundane than complex hacking tools.

"There is one vulnerability that never lets me down," Fallon says, "stupid users." Fallon calls the people she doxxes "marks," and says stupid marks are the easiest to dox. Sometimes, she claims, it will only take her a few minutes.

But no matter the intention, the outcome of a dox can be unpredictable. Fallon says her team was behind the August doxxing of Corey Klicko, a former Wisconsin leader for the Nationalist Socialist Movement. After Klicko's details were published on the anarchist site Enough Is Enough, he canceled a meet-and-greet barbecue sponsored by the National Socialist Movement, and distanced himself from the group.

"After careful consideration and communications with positive people, I've decided to break away from anything that may be perceived as negative to myself, my family, or the community," Klicko told local media. "Racism and hate have no place in communities and we all need to move forward to better provide for our future."

But it can go the other way. When neo-Nazi podcast host "Mike Enoch" was doxxed by right-wingers on 8chan's /pol/ board as New York Web developer Mike Peinovich in January of 2017, it was revealed that his wife was Jewish. In the weeks that followed, the so-called alt-right reeled from the revelations. It appeared to be the end of Enoch's fringe fame. But he bounced back, separating from his wife and embracing his newly public persona in the white nationalist movement. He continues to podcast and appear at rallies. If anything, being doxxed has hardened Peinovich's views.

This is a possibility that worries George Hawley, author of the new book Making Sense of the Alt-Right. "One could argue that doxxing is counterproductive," he writes, "since doxxing victims will have no disincentive to stop creating Alt-Right content after being revealed. Indeed, they may become even more energetic and well known, as they no longer need to hide their identities."

But Hawley also argues that doxxing works beyond the individual. "While doxxing is not necessarily a useful means of silencing one particular voice, it may have greater unseen effects: it sends a message to others, encouraging them to stop their work in the 'alt-right' or dissuading them from getting involved in the first place," he writes.

Every dox that Fallon works on goes through several levels of verification, she says. She's always looking for a region, a location, and, ultimately, a home address. "We like to have at least one solid recent proof of the residence, but three is considered pretty golden." This proof could be a voter registration record, property ownership record, or a court record. "We talk about ethics all the time in our teams," she says. Fallon says they are wary of "stale information," like a seven-year-old traffic ticket that might lead to an address where the mark no longer lives.

"We're very careful about what we publish," she says. "It is very important not to dox the wrong person. I never publish anything until I have validation of the data."

And sometimes this data is hard to find. Some "marks" have better security. They might use fake online profiles, which Fallon calls "socks." (These kinds of fake online profiles aren't limited to antifa and the so-called alt-right. They're used prolifically on the Internet by catfishers, con-artists, and, most recently, by Russian bots and trolls involved in disinformation campaigns.)

Fallon says there are four types of socks. The first is a legitimate account with "signal interference." This means the person might have an extremely common name, like John Smith, that makes them hard to pick out. Or they might share a name with a B-list celebrity. Searching for them involves wading through results about another person.

The second is what Fallon calls "a poorly made sock." This is a false account created hastily, without much care. The person might use a fake name, but still add all their real friends. Or they might "friend" their fake account with their real account. All these things make the sock vulnerable. In the case of poorly made socks, Fallon says she often finds people through their girlfriends or wives. "If I can't find the guy, I can always find their woman," she says. "The women aren't as careful. They rate things, they review things on Facebook and you know it's near where they live."

The third is a "well-made sock." These are false identities where people have taken real care to conceal themselves. Fallon says these often take a few hours or even days to crack. "It's never perfect," she says. She says can still find their identities through partners, parents, or adult children.

Finally, there's what Fallon calls "a perfect sock." These are rare cases, she says, where people are so conscious of their cybersecurity that they have hidden themselves almost completely. Nonetheless, she says, they still make mistakes, if you look hard enough.

Using herself as an example, Fallon shows me a slide with a screenshot of a Facebook message. She laughs. This is a message she received from her high school sweetheart who found her on Facebook, despite her security precautions and fake name. This is a lesson. "I have really good security on the Internet," she says, "and yet I can be found." As Fallon has already told me, no sock is truly perfect.

What does this all mean for the doxxing battle between left and right? White nationalist Richard Spencer, who was punched in the face by a masked antifa member on the day of Trump's inauguration, says he doesn't believe that doxxing will halt the growth of the so-called alt-right in the long run.

"You can't really be a leader unless you show your face," Spencer told ProPublica, but he believes not everyone has to be as public as he is. "One probably can't work at a corporation or a law firm, or so on. But there are plenty of ways of managing this difficulty."

He maintains that the "alt-right" is growing, and has the tacit sympathy of many white Americans. At some point, he believes, the movement will be so big that doxxing will no longer have any effect.

Some scholars also question whether doxxing will work to stop the far-right, though for different reasons than Spencer. Ajay Sandhu and David Marciniak, scholars of big data at the University of Essex in the United Kingdom, recently blogged about white nationalists' right to privacy in the face of doxxing.

"Is [doxxing] even an effective method of fighting fascism?" Sandhu asks. "Is this an effective means of challenging racist views?" Sandu and Marciniak argue that doxxing simply isolates people, forcing them into smaller parts of the Internet. "You don't really challenge them, you allow them to exist in those isolated spaces," Sandhu says.

This is something Fallon acknowledges, but it doesn't worry her. "I don't mind them being keyboard warriors in their tiny little echo chambers," she says. She just doesn't want them to feel empowered enough to take action in the real world.

Thus Fallon says she is unwavering in her belief in doxxing. "It's non-violent. It's transparent. It's validated. It's effective," she says. "I feel like, for me, if there was one thing that I could say to the alt-right and to fascists it would be: 'You don't get to be a Nazi on the weekend.'"

She said she wants people to take responsibility for their words and actions. "If you're a Nazi on Saturday, you're a Nazi all goddamn week," she says.

On October 5th, about a month after I observed Fallon's training session on doxxing, a Tennessee chapter of the left-wing group Anti-Racist Action published a "communiqué" on Facebook. Anti-Racist Action is a small, militant anti-fascist group with roots in the left-wing skinhead movement of the 1980s.

In the note, anonymous ARA members warn of the deceitful and untrustworthy behavior of other anti-fascist activists, whom they named. Among the accusations are that these other activists have "lied to gain entry into multiple groups, offered resources and withdrawn them at critical moments, spread rumors."

At the end of the ARA communiqué is a list of supposed aliases used by one of the activists they condemn. The last one catches my eye: "Fallon." They say that her real name is Jessica Nocero.

I reach out to the ARA to ask for more details, but the group never replies. John Carico, an anti-fascist activist based in Tennessee, says he is aware of the dispute between Anti-Racist Action and Nocero, among others. Carico says he's had positive dealings with Nocero, and has seen no compelling evidence of any wrongdoing on her part. In his opinion, Nocero might be being targeted because she is wealthier than other activists, and her resources make others suspicious.

I call Fallon and ask her whether she is Jessica Nocero. She says that she isn't. She tells me Nocero is just a naïve liberal who has been inappropriately identified and outed—accused of being a danger to the movement when she isn't one.

I keep searching, eventually linking the phone number I've been talking to Fallon on to one for Jessica Nocero. The modest biographical details Fallon had shared with me appear to match Nocero's.

When I send Fallon the documentation suggesting that she is Nocero, she replies: "Damn, that's a good dox!"

I write to her encouraging her to tell the full truth about herself given that she has already been publicly identified.

She says she is already getting threats online. When I ask who they're from, she says she's not sure if they're from leftists or alleged fascists.

Ultimately, she sends me a written statement, acknowledging that she is Nocero.

"I am a mother, activist, worker, neighbor, and active member of my community," she writes. She says that the majority of anti-fascist work is "community service," and that she's done other such work as a medic, community gardener, and prison activist. Defending her doxxing work, she writes, "I still believe that ethical doxxing of white supremacists and fascists is an important and effective tool in the Anti-Fascist wheelhouse."

Nocero says she has always prepared herself to be doxxed by white supremacists, or members of the far-right. "I am disheartened that I myself was doxxed by leftist activists," she says. She says she still believes in "activist unity" and "radical solidarity," and hopes that other activists experiencing doxxing do not "fall prey to paranoia and fear."

Of all the things Fallon has told me, when she was anonymous and after her public doxxing, there's one thing that stays with me, repeating in my mind. "No sock is perfect."

This post originally appeared on ProPublica as "Info Wars: Inside the Left's Online Efforts to Out White Supremacists" and is republished here under a Creative Commons license.