It used to be that a relatively small percentage of college students did internships. Back in the early 90s, it was something like 8 percent. But things have changed: students, hungry for every advantage they can get when they graduate into a competitive job market, are applying for them at an astonishing rate -- the National Association of Colleges and Employers found that 83 percent of graduating students had held internships in 2008 -- and employers, loathe to turn down free labor in a tough economic time, are happy to fill their ranks with bright young go-getters who work for nothing.

Except, it's not free labor. At least, according to the Department of Labor, which has been handing out fines to companies for internship-related infractions left and right, it's not supposed to be. The New York Times has a great article on the explosion of possibly-illegal unpaid internships in the U.S., and it quotes some of the official legal criteria that differentiate an unpaid internship from just plain unpaid work:

"¢Â The training, even though it includes actual operation of the facilities of the employer, should be similar to what would be given in a vocational school or academic educational instruction
"¢ The training is for the benefit of the trainees
"¢ The trainees do not displace regular employees, but work under their close observation
"¢ The employer that provides the training derives no immediate advantage from the activities of the trainees, and on occasion the employer's operations may actually be impeded

In other words, the employer's role is as a kind of benevolent vocational educator. Does that sound like any internship you've ever had? The Times article quotes former interns who make their experiences sound like Cinderella's: janitorial work, stuffing envelopes in a back room -- one young woman spent part of every day disinfecting every doorknob in the film production office where she worked, to guard against the spread of swine flu. And paid employees have complained about their jobs being displaced by small armies of interns.

Yeah, some internships involve menial work. That's part of the job. But if that turns out to be most of the job, well, according to regulators that's a violation of the law.

How was your internship?