It’s the time of year when college students are thinking forward to their summer plans—and many are applying for internships, often without any prospect of pay.

Unpaid internships have become nearly ubiquitous in industries like politics and entertainment, where young or inexperienced workers may be willing to work for no compensation in exchange for the opportunity to “break in” to a competitive field. They also prevail in journalism and in the nonprofit sector.

Nonprofits, political campaigns, and government agencies often insist that they depend on unpaid interns to do work that would otherwise not get done with limited budgets – and to train new workers and identify good candidates to hire for jobs.

Indeed, internships are considered to be good career training. Many universities require their students to complete an internship and sometimes require that internship to be unpaid. According to a 2012 study by InternBridge, at more than two-thirds of universities, some or all students are required—by either their university or department—to work unpaid internships . (Many of these students receive academic credit for their unpaid internships).

Yet despite their ubiquity—and the fact that they’re required by some universities—many unpaid internships are barely legal. According to the Department of Labor, for-profit companies are legally required to pay their interns if the intern is doing a job that benefits the company in any way. If a company hires interns who displace paid employees or who don’t receive educational training at their internship, then they must pay minimum wage to those interns.

In fact, former interns of a few high-profile entertainment companies have recently sued their employers for failing to compensate them for legitimate work that was beneficial to the company. Over 300 former unpaid interns who had worked for Viacom and its television networks, including MTV, filed suit in 2013. Just two weeks ago, Viacom settled the case, agreeing to pay up to $7.2 million. Former unpaid interns of NBCUniversal and Fox Searchlight Pictures have reached similar settlements.

Writer Daniel Akst has argued that unpaid internships often perpetuate privilege because only those with wealthy parents can afford to work for no pay. “Unpaid internships are a great way of giving the children of affluence a leg up in life," Akst wrote in the Los Angeles Times. "If they really do help young people get permanent jobs in desirable fields, then the current internship system has the effect, however unintended, of reserving this advantage mainly for well-to-do families — families that happen to be disproportionately white.”  While some employers provide their interns with transportation or parking stipends, others neglect even this. A former intern of the Cincinnati Enquirer noted that the paper required interns to pay $50 per month for their own parking. With respect to these on-the-job costs, young people with privilege may feel more confident or empowered to ask for their employers to cover transportation costs or provide stipends.

Some have argued that paying interns would simply result in the same affluent interns getting paid for their work. Yet, there are structural issues that prevent working-class young people from accepting, or even considering, unpaid internships. Paying all interns not only opens up industry training and resume-building opportunities to more young people—it also complies more closely with the standards set by the Department of Labor.

If you’ve had an internship that you should have been compensated for, but weren’t, you can file a confidential complaint with the Department of Labor and potentially collect back pay. ProPublica provides a resource guide for filing this complaint.