In the ruling, the judge said unpaid internships should be allowed only in very limited circumstances.

Judge Pauley rejected the argument made by many companies to adopt a “primary benefit test” to determine whether an intern should be paid, specifically whether “the internship’s benefits to the intern outweigh the benefits to the engaging entity.” Judge Pauley wrote that such a test would be too subjective and unpredictable.

Instead, the judge forcefully called for following criteria that the Department of Labor has laid out for unpaid internships. Those rules say unpaid internships should not be to the immediate advantage of the employer, the work must be similar to vocational training given in an educational environment, the experience must be for the benefit of the intern and the intern’s work must not displace that of regular employees.

Some employers have asserted that they have free rein not to pay interns as long as the interns are receiving college credit. But Judge Pauley said receiving academic credit was of little importance in determining whether interns should be paid.

“Undoubtedly Mr. Glatt and Mr. Footman received some benefits from their internships, such as résumé listings, job references and an understanding of how a production office works,” Judge Pauley wrote. “But those benefits were incidental to working in the office like any other employees and were not the result of internships intentionally structured to benefit them.” Judge Pauley added that “Searchlight received the benefits of their unpaid work, which otherwise would have required paid employees.”

The “Black Swan” case was the first in a series of lawsuits filed by unpaid interns.

In February 2012, a former Harper’s Bazaar intern sued Hearst Magazines, asserting that she regularly worked 40 to 55 hours a week without being paid. Last July, a federal court ruled that the plaintiff could proceed with her lawsuit as a collective action, certifying a class of all unpaid interns who worked in the company’s magazines division since February 2009. This February, an unpaid intern sued Elite Model Management, seeking $50 million.

After a lawsuit brought by unpaid interns, Charlie Rose and his production company announced last December that they would pay back wages to as many as 189 interns. The settlement called for many of the interns to receive about $1,100 each — amounting to roughly $110 a week in back pay, for a maximum of 10 weeks, the approximate length of a school semester.

As part of his ruling on Tuesday, Judge Pauley also granted class certification to a group of unpaid interns in New York who worked in several divisions of the Fox Entertainment Group.