Tens of thousands of people who took out private loans to pay for college but have not been able to keep up payments may get their debts wiped away because critical paperwork is missing.

The troubled loans, which total at least $5 billion, are at the center of a protracted legal dispute between the student borrowers and a group of creditors who have aggressively pursued them in court after they fell behind on payments.

Judges have already dismissed dozens of lawsuits against former students, essentially wiping out their debt, because documents proving who owns the loans are missing. A review of court records by The New York Times shows that many other collection cases are deeply flawed, with incomplete ownership records and mass-produced documentation.

Some of the problems playing out now in the $108 billion private student loan market are reminiscent of those that arose from the subprime mortgage crisis a decade ago, when billions of dollars in subprime mortgage loans were ruled uncollectible by courts because of missing or fake documentation. And like those troubled mortgages, private student loans — which come with higher interest rates and fewer consumer protections than federal loans — are often targeted at the most vulnerable borrowers, like those attending for-profit schools.