Two years ago, they didn’t stand a chance.

Two days ago, when I heard they had won, I dug the e-mail out of my inbox: “I’ve been glad to read about your upcoming book, Intern Nation. I recently worked as one of approximately 20 illegally unpaid interns for the Oscar-nominated film Black Swan.”

The e-mail was from Eric Glatt, a 41-year-old New Yorker who admitted that he fell “outside the norm” for an intern, with his two Master’s degrees and substantial career experience under his belt. Like many older interns in today’s labor market, he was transitioning careers and had no idea how brutal it would be. In 2010, he worked hundreds of hours on the set of Black Swan, doing the essential work of drawing up purchase orders, making spreadsheets, running errands — and earning nothing for his work, not even the minimum wage of $7.25 an hour. There was no training. There were no full-time jobs waiting at the end of the rainbow. “Win-win” was an empty platitude. The reality was that Glatt’s “employer” was getting something for nothing.

Black Swan went on to make over $300 million. Fox Searchlight Pictures, Glatt’s employer, is a subsidiary of Rupert Murdoch’s News Corp., with annual revenues around $35 billion. Learning afterward that his internship had been against the law, and that he was far from alone, Glatt e-mailed me to ask if I knew a lawyer who would take on his case. No intern had filed a case like this before, I told him, but I put him in touch with Adam Klein of the New York City firm Outten & Golden. (Just to be clear: I received no compensation for connecting them, and have no financial stake in the case.) Within a month, Glatt and fellow plaintiff Alex Footman had filed against Fox. Interns are used to being laughed at, but all of a sudden things were deadly serious.

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In the resulting lawsuit, the small amount of backpay at stake was secondary. The case was first and foremost a challenge to the ugly new culture of internships, a third to half of which are unpaid. It was a culture I knew firsthand, both from my own internship experience and from interviewing hundreds of interns for Intern Nation, published in 2011. Though a small minority of unpaid internships are legitimate and exemplary, the more accurate term for Glatt’s experience is wage theft, which affects millions of American workers every year. In fact, the Black Swan internship was in many ways typical both of the film industry and of broader economic realities. At their peak following the 2008 crash, unpaid internships were increasingly crowding out paid ones and replacing regular positions altogether, in the process turning the entry-level job into an endangered species. It was “a capitalist’s dream,” as sociologist Andrew Ross put it: free white collar labor made to seem almost entirely normal. This pay-to-play system was not only exploiting the interns, but also excluding the poor and working class from a whole range of fields and opportunities. Most people simply can’t afford to work for free, of course, and you just can’t pay the rent with on-the-job experience, CV-line items and letters of recommendation.

But most interns accept it as standard practice, however unfair — or else are afraid to stick their necks out. Indeed, many people told Glatt that his case was “career suicide.” But he went ahead anyway. “If you don’t come forward and speak up, you’re basically stuck,” he says. “It was nauseating to see how easily employers could get free labor just by slapping the title ‘internship’ on something.”

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The decision rendered on Tuesday by Judge William H. Pauley in Manhattan’s Federal District Court fully vindicates Glatt and his fellow interns, proving that the law still holds. Most interns at for-profit companies are entitled to be paid minimum wage and overtime, and to receive the same workplace protections as other employees. Those rights date back to the Fair Labor Standards Act of 1938, the central piece of legislation that protects American workers. A 1947 Supreme Court decision, Walling v. Portland Terminal, established a narrow, common-sense exemption for those enrolled in a genuine training program. But few internships these days are serious about training, and — as in this case — most don’t even pretend. What started out in hospitals long ago, and later turned into a well-intentioned corporate recruiting and training tool, has become in recent decades something altogether different. Unscrupulous employers quietly drove a truck through the Walling loophole; schools made it official with academic credit and internship fairs; government looked the other way; and desperate young people have to play along.

Fox is reportedly considering an appeal, knowing that the Black Swan case is just the tip of the internship iceberg and reluctant to let the precedent stand. But the interns are confident. “I think we have a clear-cut case,” says Glatt, “and the higher it goes, the more the reasoning is affirmed and the better it is for labor, for workers, for students, all across the country.” According to one of the interns’ lawyers, Juno Turner, the next step is to apply the reasoning in this decision to an estimated 100 to 150 Fox Searchlight office interns who were certified as a class by Judge Pauley on Tuesday in a quieter but equally important victory.

(MORE: The Beginning of the End of the Unpaid Internship)

At least six similar lawsuits have been filed in the wake of Black Swan, in fields such as fashion, sports, television and modeling. All are still pending, except one against television personality Charlie Rose, which settled out of court. “There are a couple [of cases] in the pipeline as well,” says Turner, noting that “once we start winning and having successful outcomes for people, we tend to see a lot more claims. I would hope that companies would take note of the decision and take a hard look at their internship programs.”

Summer is often seen as internship season, even if the sad reality is that unpaid work is now a year-round phenomenon. But this summer may prove a turning point: it might just mark the beginning of the end of the unpaid internship.

Ross Perlin (@rossperlin) is the author of Intern Nation: How to Earn Nothing and Learn Little in the Brave New Economy.