This week's episode of The Key explores why some institutions use those policies and why consumer advocates think they're pernicious, even though they're only a small fraction of the $1.7 trillion student debt problem in American higher education.

Martin Kurzweil, director of the institutional transformation program at Ithaka S+R, discusses research on what it calls “stranded credits” that colleges sometimes hold hostage from former students and a promising experiment that could offer a way out for students and colleges alike.

Melanie Gottlieb, executive director of the American Association of Collegiate Registrars and Admissions Officers, explains why many higher ed officials oppose potential federal regulation to ban such policies, but acknowledges the need for colleges to limit the kinds of debt they try to collect from students.