One evening in Chiang Mai, Thailand, toward the back of a modest two-story building in one of the city's 17 unofficial red-light districts, a handful of sex workers primped. They pinned back straight hair with small barrettes and applied various hues of rose blush. Occasionally, an iPhone would ding, prompting the women to check who had received a text from a client. On the wall, a poster read: "It's not what we do... it's how we do it." Graffiti scribbled in pink and purple on another wall nearby was more direct: "Blow Jobs are Real Jobs!"

Hermarratanarapong turned me from watching her friends preen to face a large cabinet with glass doors. Inside were T-shirts that read "Good girls go to heaven, bad girls go everywhere," flash drives disguised as lipsticks (for easy access to labor law documents), and handwoven condom-carrying cases. There was an anthology of autobiographical vignettes written by group members, a history of sex work in Chiang Mai, and something called the Bad Girls Dictionary—a self-published book full of feisty definitions for more than 200 words relevant to Empower's mission. I flipped through, jotting down a few:

Empower's headquarters, where I met the women, serves not only as a dressing room but as a library, schoolhouse, and drop-in centre for thousands of sex workers throughout the city. (Empower is short for "Education Means Protection of Women Engaged in Recreation.") The building houses the organisation's nightclub as well. In the Can Do Bar, women are employed as waitresses and receive social security benefits and vacation and sick days.

"We are workers, not victims," Lily Hermarratanarapong, who wore tight turquoise capris and a shirt speckled with sequins, told me. She and her colleagues belong to Empower, a sex-workers' rights organisation with an estimated 50,000 members. Since the group's founding in 1985, it has fought to improve the working conditions of women in the sex trade in Thailand, where prostitution is illegal, but widely tolerated. Empower members advocate for the decriminalisation of sex work; they want the industry treated like any other profession.

In Thailand, Hermarratanarapong and her colleagues believe this approach has created problems for those who willingly enter the profession. According to Richard Howard of the Bangkok office of the International Labor Organisation, less than ten percent of sex workers in Thailand are "trafficked"—duped, tricked, or forced into their circumstances. "Ninety percent are there because they made the decision to do it," he said. A 2012 research report compiled by Empower details a host of abuses related to treating these women as trafficking victims, including widespread police entrapment, wrongful detention, extortion, invasive medical examinations, and unjust deportation. It concludes: "We have now reached a point in history where there are more women in the Thai sex industry who are being abused by anti-trafficking practices than there are women being exploited by traffickers."

Raids are a primary tactic for curbing the sex trade in Thailand and worldwide. They are part of what critics call a "criminal justice" approach toward stopping prostitution, whose adherents believes all aspects of the trade should be illegal. In part, the strategy grew out of a consensus formed in the early 1990s among some human rights groups, religious fundamentalists, national governments, and agencies like the United Nations that considered a prolific sex industry antithetical to civilised modern society. Raids of brothels and clubs, followed by the detention and prosecution of traffickers, and therapy and skills training for victims, became the norm.

Raids [of brothels]: A hero or rescuer's job, action taken by police with TV cameras, reporters, where many women are shown sitting on the floor and hiding their faces... or with their eyes inked out like criminals—when the job [is] done, most of us end up in debt and return to work to pay it off after [we] are released.

Dignity: The feeling we have when we do a good job, with professionalism and skill; the feeling we have when we pay off our debt... when our daughters graduate from university... when we put a new roof on our family home.

This stance has put Empower at odds not only with the Thai government but also with many Western feminists. Recently, a draft proposal by Amnesty International advocating decriminalisation of the sex trade was leaked, and in the summer of 2015, the Twitter-sphere was ablaze with censure, including the likes of Lena Dunham and Gloria Steinem. "Why would [Amnesty] call on the decriminalisation of exploiters of [the] most marginalised human beings on the planet?" said Taina Bien-Aimé, the director of the Coalition Against the Trafficking of Women (CATW), a US-based nonprofit. Her organisation penned a letter denouncing Amnesty's position; more than 100 celebrities, world dignitaries, and human rights advocates signed it. When asked about the fight between those who consider all people engaged in commercial sex to be victims, and those who consider them to be workers, Bien-Aimé replied: "It's a war."

Empower has pushed the Thai human-rights community to reconsider its reliance on raids, rehab, and criminal prosecution as the go-to approaches to combat trafficking, fundamentally questioning whether the sex industry ought to be deemed illicit. The organisation has become one of the leading voices in Southeast Asia and throughout the world, advocating decriminalisation of the trade as the best option for the people involved in it. Empower wants the Thai government to start treating trafficking and exploitation as aberrations rather than the norm, and it hopes to rout out abuse as you would in any other industry.

When the war ended, vacationing soldiers disappeared, but the sex industry did not. It thrived throughout the 1980s, while the country's blossoming tourism industry was creating new job opportunities in cities for impoverished migrants from the countryside. The country's north was poppy farming territory, and new government opium eradication programs destroyed many families' livelihoods, including those of the young women who worked the fields alongside men. Poverty was exacerbated by the fact that half of the country's ethnic minority groups did not have citizenship, making it harder to get formal employment and preventing them from owning land. For many young women, says David Feingold, an anthropologist who has studied rural Thailand for decades, "the best option was to get involved in sex work."

The origins of Thailand's sex industry go back centuries, but the Vietnam War gave it the greatest boost. In 1967, in an attempt to raise morale among American soldiers, the US and Thailand signed a pact to allow troops stationed in neighbouring Vietnam temporary leave in Thailand, which was relatively safe and stable. Thailand used financing from Chase Manhattan and Bank of America to set up "Rest and Recreation" sites, where brothels were the main attraction, according to Casting Stones: Prostitution and Liberation in Asia and the United States. Over the course of the war, it's estimated that at least 700,000 US soldiers visited R&R sites as a reprieve from the stress of combat.

On that night in Chiang Mai, the women didn't take the time to ruminate on whether their ideas would soon cause such a highbrow kerfuffle. Despite their activism, those in Empower say they are, above all, hardworking professionals who spend most of their time focused on their jobs. Now dark outside, their workday was about to begin. Around 8 PM, some went off to pre-arranged meet-ups with clients; others hedged their bets and sought customers by hanging around one of the city's hundreds of bars, karaoke joints, and massage parlours. I watched as the women grabbed condoms from a basket on their way out the door. Left behind was Mai Jakawong, a slim, elegant woman with an angular face and jet-black hair. That night, she would be working in Empower's Can Do Bar, where she planned to meet customers. "If you're a sex worker," she said when I asked her about the controversy, "you're seen as either a sad girl or a bad girl. 'Sad' if you've been forced into this. 'Bad' if you choose to be here." She paused, watching her friends saunter out the door. "But what if we aren't either?"

Pi Noi held the classes on sidewalks; the students would pull bar stools out during the day and learn useful phrases. The English classes, she told me recently over Skype, were "to help minimise exploitation." Pi Noi chafed at the idea that the women were powerless victims just because they had been forced or sold into their current situation. The sex workers, independent and tough-minded, were already accustomed to thinking of themselves in this way—Pi Noi simply helped them find a language to assert their independence. Even with minimal English, she says, women "could express what they wanted and didn't want, how to say yes or no. This is the basis of human rights."

It was around this time that a Thai woman named Khun Chantawipa Apisuk, who's known as Pi Noi, moved back to Bangkok from Boston, where she had relocated with her husband a few years earlier to study sociology. She settled near Patpong, the city's burgeoning red-light district, and started hanging out in some of the bars. She struck up friendships with the women there. Since Pi Noi spoke some English, they asked for lessons, so they could better communicate with their customers, many of whom were American or European.

Promising glamour and riches, pimps lured in thousands, and they took many of the women to dilapidated brothels in Bangkok, Chiang Mai, and the beach haven of Phuket. Often with financial arrangements akin to indentured servitude, the women were prevented from leaving the premises and could not communicate with family. The pimps also frequently raped their employees. When the HIV epidemic emerged, the effect was staggering. According to multiple local studies, in the late 1980s in Chiang Mai, an estimated 44 percent of sex workers were HIV positive.

By the late 1990s, the sex industry in Thailand was again shifting dramatically. The brothel as the hub for activity was dying out. The economy had improved, meaning there was less desperation driving women into unknown and often dangerous situations. The Ministry of Health instituted a mandatory condom policy in brothels, threatening to close them down or extort high fines if STD rates didn't diminish. Feingold, the anthropologist, says that this began to chip away at the formerly lucrative brothel model that was based on flagrantly ignoring worker welfare and safety. "The sex business didn't become unprofitable," says Liz Hilton, an Australian volunteer who's worked with Empower for more than 20 years. "Exploitation became unprofitable."

As women gathered, they started conversing about other issues like the brothels' deplorable conditions, disease, and debt. In 1987, in cooperation with a local doctor, Pi Noi created a sex worker clinic in Bangkok to provide women with reproductive health workshops and free condoms. (In 1994, Empower officially became an NGO and a foundation itself.) Pi Noi reached out to the brothel owners directly, asking that they let their employees come to learn about HIV prevention and to offer Thai language classes to migrants. Many owners assented. Even though Pi Noi was radicalising their employees, brothel owners were more than happy to receive help trying to keep their workforce alive.

According to Thai legislation, in order to be fined or jailed, prostitutes or their clients must be caught in the act of soliciting, advertising, recruiting, arranging—or engaging in—commercial sex. In practice, according to Hermarratanarapong, this means police officers bide their time—and supplement their salaries— through entrapment schemes. To avoid government fines, she claimed women's salaries are regularly siphoned off to pay the cops. If the sex worker is an undocumented immigrant, she said, the bribe price is doubled or tripled to prevent deportation.

One evening in Chiang Mai, Hermarratanarapong, Jakawong, and two other Empower members tried to explain their lives to a group of US college students on a semester abroad program in Thailand who were studying local economic issues. "When you are a sex worker, you always start with the police," Hermarratanarapong told them, as they sat in a circle on the dance floor at the Can Do Bar. "Most of the dangers in sex work come from the law," she said. There was the constant threat of raids, but that wasn't all.

"If you're a sex worker," Mai said, "you're seen as either a sad girl or a bad girl. 'Sad' if you've been forced into this. 'Bad' if you choose to be here." She paused, watching her friends saunter out the door. "But what if we aren't either?"

By 2002, business had moved to "entertainment zones," or defacto red-light districts. Even though prostitution was still illegal, the economy depended on it, and that year, the Thai government allowed for the legal establishment of massage parlors, karaoke bars, and billiard halls that clandestinely doubled as places for men to meet prostitutes. Each zone normally spans several city blocks, where sex workers are employed as servers, masseuses, and dancers. Customers know to look here for sex, and the sex workers take clients off-site.

The presenters said that's the main reason Empower started its own place: the Can Do Bar. The students seemed embarrassed at being prompted to take in their surroundings, which included a lot of phallic art, posters of almost-naked women, and abrasive graffiti. ("For a long time, we had been making suggestions to the government," Jakawong had told me about the bar. But "nobody was getting it. So we built it ourselves.")

Perched on a bar stool in a pink dress, a woman named Neung told the group "because there is no labor protection, working conditions are made up by the employer." These "bar rules," as they're known, include sex workers being docked pay for weighing more than 110 pounds, arriving late for a shift, or falling behind in male clients. There are also drink quotas; each worker, Neung said, has to have "so many drinks bought for you every month. It doesn't matter if you are pregnant or don't drink." I was later told it's possible for quotas to reach as high as 150 per week.

"If we can speak a little [English], we have a better chance of having a good night," Hermarratanarapong told me. Over the course of the following hour, two students went through the vocab and sentences, reciting each aloud. (They asked for my help with pronunciation but said they normally rely on an iPhone app). They also tried a conversation in English, which didn't go particularly well. Before class ended, Hermarratanarapong assigned homework: transcribing and translating a favourite American pop song.

On a different day, I watched Hermarratanarapong as she led one of Empower's English classes. On a dry-erase board, she wrote the words "need," "want," "meet," "drink," "end," and "stop." Then she added sentences: "You can call me tomorrow," "I will wait until the bar closes to go," and "I have to send money to my family."

Hermarratanarapong, too, had worked in factories, but she admitted that her motivations weren't purely economic. "My generation was the first to have TV," she said of her childhood in Chanthaburi, a city in southern Thailand. "Seeing the exciting lives on the screen made me start to ask, 'Why? Why are we following all these rules?'" When she moved to Bangkok, she found work in factories, as a pole dancer, and in a bar where she was a paid escort. She made more money in a week from being a flirtatious companion for men, she said, than she had in a month at the factory. It took her years to finally sleep with a client, and when she did, she thought, What's so bad about this? She added: "Being a sex worker isn't about lack of choice. If I really had no choice, I'd be working in a garment factory." According to the International Labor Organization, only ten percent of human trafficking victims in Asia are trafficked for commercial sexual exploitation. "The claims of millions of new [trafficking] victims annually are bogus," says Ronald Weitzer, a sociologist at George Washington University who's an expert on the sex trade. Many people enter the industry for financial reasons. Thailand's legal minimum daily wage is approximately $8.40 per day, and many women in the informal sector are paid even less. The sex workers I spoke with in Chiang Mai said that while their income ranges considerably, even on a bad night they make at least $14.

The students were curious how each of the women started in sex work. Jakawong told them she had worked a number of jobs, most recently in a bakery, where she was bored. Neung, in the pink dress, had done knitting and sewing. She said she had been to "all of the factories I could go through."

I tried to tease out what happens when there are no warning signs. But Empower members are reluctant to admit that sex work entails dangers not typically encountered in, say, a garment factory. As we spoke, six other Empower members arrived and prepared a shared lunch; they all said they had only one or two truly scary situations. When I pressed for details, the room grew tense. Wan told me that when one of her customers stole her purse and clothes and took off without paying her, she wrapped a towel around herself and asked the hotel staff to pursue him, but they refused. Others didn't want to recount specific horror stories because, they said, that's all journalists ever report on. They pointed me toward the book of autobiographical vignettes, which contained some troubling incidents. In one chapter, the author (all entries are anonymous) went to a hotel with a customer, and when she emerged from the shower, she found four other men in the room demanding group sex. She refused. When one man moved to grab her, she quickly picked up the TV and threatened to throw it, saying they'd be charged for the damage. The men backed down. In another case, a high-ranking military officer brought a gun into a massage room and raped two women.

"We always tell each other about the bad ones," a tiny woman with clear braces named Wan explained on a different day. It was noon, and we were in the Empower library. Wearing a pink and white sweater, Wan picked at a packaged chocolate chip muffin. She said that word about abuse spreads quickly, and this helps keep workers safe. Once, Empower made posters with a picture of the face of a man who raped one of its members and circulated them in the city's bars. Wan added, "There are often signs in the bar. If he pinches or smacks you in public, he will be worse in the room."

Empower also helps sex workers finish their Thai schooling by providing tutoring, study space, and contacts for continuing education programs. At least several thousand women have gone through Empower's classes, including Hermarratanarapong, who got her high school equivalency through the program. At last count, 67 were currently enrolled in alternative high school programs, and there are more than 100 college graduates now—women who may or may not continue with sex work. "We don't ask," Hilton, the Australian woman who's worked with Empower for more than two decades, had told the US study abroad students. "That's their decision. Empower isn't about changing sex workers. It's about sex workers changing society."

When I asked Bien-Aimé about the evidence that women who choose to sell sex outnumber those who are forced into the trade, she was skeptical that those lines could be so neatly drawn. "How would you distinguish between someone with absolute negotiating power with clients and the majority of individuals who enter [the sex trade] before [the age of] 18" and are "sold into it by intimate partners?" She added: "We don't want this to be a numbers game. Let's listen to the survivors."

According to Empower's critics, these situations make abuse of prostitutes fundamentally different from other kinds of worker exploitation. "There would be no commodification of women in an equal world," CATW's Bien-Aimé told me via Skype after I returned from Thailand. Prostitution, she believes, can never be just work, so decriminalisation is a flawed premise. "Prostitution [is a] cause and consequence of gender inequality."

Before Bien-Aimé and I ended our call, she added that her opposition to decriminalisation is based in both theory and practice. "It's a total failed experiment," she said. Germany, New Zealand, and Australia have all decriminalised the industry, she explained, listing the problems this has wrought. After we spoke, she sent me an email full of links to studies backing up these claims, including a lack of improvement in the earnings of sex workers and testimony from law enforcement officers who say they struggle to contain trafficking, violence, and organised crime in the new environment. In Germany, doctors who work with sex workers in the decriminalised industry say their clients are so severely damaged that a German physicians' association has formally asked parliament to repeal the law.

The way for journalists to speak with trafficking survivors—those who, unlike the Empower members I met, did not willingly choose to enter the sex trade—is typically through nonprofit organisations that work directly with this community. In Chiang Mai, three organisations refused my request for interviews. Back in the US, Bien-Aimé tried to facilitate this connection for me with two more groups. One did not respond to repeated requests, and the other said no because, in Bien-Aimé's words, it had a policy to "not provide interviews to any media platform that endorses or appears to endorse prostitution as 'sex work' or the sex trade as a viable occupation."

Empower's criticism of raids and rescues is not just directed toward the Thai government. It is also focused on a global framework—personified by the "hero NGO" or Bien-Aimé's CATW—that detractors call the "rescue industry," an unlikely alliance between anti-prostitution feminists and the religious right forged to fight the commercial sex industry. Critics believe the rescue industry has purposefully conflated sex work and sex trafficking, with "a crusade against the former [being] seen as synonymous with a victory against the latter," according to Feingold, the anthropologist who's researched the sex industry for decades.

Before I left Chiang Mai, Hilton set up a laptop in front of me and clicked play on a loaded video: "Last Rescue in Siam," a black-and-white silent satire that Empower members made several years ago. Set to a Charlie Chaplin–esque sound track, the film depicts an anti-trafficking raid carried out by three awkward characters: a policeman, a social worker (a conservatively dressed woman with glasses and a clipboard), and a "hero NGO" (a woman in a cape). The three, plus a pickup truck full of bumbling cops, descend on a bar where sex workers are amiably flirting with potential clients. Chaos ensues. Rescuers manage to nab only one woman, who says she's 19 but who the authorities believe is 16. She's subjected to a dental exam—a common but dubious method used to determine age—and then locked in a room labeled "rehab." With the sewing machine she's been provided, she sews herself an escape ladder and runs directly back to the bar. She's greeted with cheers and hugs from the other sex workers. "We hope that's the end," the screen reads.

To Hermarratanarapong, the lock-up-the-johns approach is irrational. "Why would we want to criminalise our customers?" she said. "They are our business. We don't need more punitive measures. [The Nordic model] is based on the idea that the sex industry is something that should eventually be eliminated. We do not agree."

She and others in the anti-trafficking movement, including New York Times columnist Nicholas Kristof, have embraced what's known as the Nordic model, which criminalises anyone who buys or enables the buying of sex. "[It] looks at the sex trade as another system of violence and oppression," explained Bien-Aimé. Research and reporting on this model, like that in favour of decriminalisation, is contradictory. For almost every study that lauds the Nordic model, there are testimonies, often from sex workers themselves, who rebuke the policy as problematic.

Since Bill Clinton's Trafficking Victims Protection Act of 2000, vast public resources have been made available to groups loosely claiming an "anti-trafficking" agenda. This money has led to the creation of NGOs throughout the world, including several in Thailand. Organizations that refuse to take an "anti-prostitution" pledge are ineligible for US financial aid. From 2001 to 2010, almost $1.5 billion US taxpayer dollars went to the global anti-trafficking fight, and in 2014 the government distributed $18 million to groups fighting sex trafficking.

Empower made "Last Rescue in Siam" to draw attention to the fact that many women have no desire to be rescued. Jakawong, who had been polishing glasses as I watched, told me that although the film is humorous, raids are no laughing matter—especially for migrants. Jakawong is originally from Burma, and her family emigrated from there when she was a child. But when she started doing sex work many years later, she was still undocumented. Her biggest fear at the time was being caught in an anti-trafficking rescue. Had this happened, she would have likely been carted off to a government shelter named Baan Kredtrakarn, which is located on an island off the shores of Bangkok.

Officially, the site provides safe haven for potential trafficking victims. Residents are given rehabilitation therapy and offered classes, including literacy and yoga. But a team of Empower members toured the facility in 2012 and criticised several aspects of the shelter. According to Empower members, women are prohibited from leaving, and they are not allowed to communicate freely with friends and family. There are many migrant women being housed there, and Empower claims to have received reports that some are not allowed visitors.

I was not able to tour the facility, and the government did not respond to questions about the shelter. But Phensiri Pansiri, a representative of Focus Thailand, an anti-trafficking group that works to remove women from the facility, confirmed some of Empower's findings. She said shelter residents are not allowed to leave the premises until prosecutors figure out if she is a trafficking victim or if she can be of use as a witness in an anti-trafficking case. This process, said Pansiri, normally takes between one and two years. If the woman is a migrant, regardless of how the investigation pans out, she will be deported—because she is either guilty of breaking Thai anti-prostitution laws or because Thai policy for trafficking victims is to send women home, regardless of where home may be. (I tried to locate former residents of the facility but was unable.)

It's estimated that there are upwards of 3 million migrant workers in Thailand. Around half are women. There are no official numbers on how many end up in the sex trade, but the fact that many of them do has led Empower to also advocate for immigration reform. According to Empower, the average rate to get across the border into Thailand from neighbouring countries is $2,000 in bribes and fees to smugglers.

While I was at Empower one day, I asked how decriminalisation would help the women and men who are forced into the trade. The group is adamant that bringing the industry out from clandestinity will help even trafficking victims, though the members don't like using that label. "Once you are 'trafficked,' you don't own your own problem," said Hermarratanarapong. "Someone decides everything for you, and that's not right." Empower's argument boiled down to the idea that extreme exploitation in the sex industry ought to be combatted just as it is in any other line of work. A comparison I heard frequently while reporting this story was: You don't make fishing illegal just because there is rampant human trafficking in the industry.

When I pushed for specifics, Hermarratanarapong told me, "It's not our job as sex workers to fix exploitation in the sex trade." She said sex workers deserved a seat at the table for discussion on these matters, but they should not be responsible for coming up with all the answers.

Then, Hermarratanarapong added with uncharacteristic severity: "This work, it isn't for everyone." She told me about a friend who went through a bad breakup, needed money, and approached Hermarratanarapong to get her a job at a bar. She told her friend to think about it first. "I am who I am, but you are who you are," she said. Just as everyone isn't cut out to be a teacher or a scientist, Hermarratanarapong told her friend, everyone isn't right for sex work. "You need a lot of skills," she said. "You have to be outgoing and good with languages and people. You have to be patient and a good listener. Sex work is only ten percent sex."

Hermarratanarapong told me she didn't get involved in Empower to be a cheerleader for the sex industry, which she knows has faults. Instead, she joined the group because she was tired of judgment from the world. She was tired of being forced into the "bad girl" or "sad girl" boxes. "I feel a sense of unfairness and frustration at how people treat me and others," she said. "And I like a fight."