Cash-strapped cities and states increasingly are trying to tap a previously overlooked pot of money – uncollected fines, fees and other costs imposed by civil and criminal courts – in order to help them balance their books.

And when people don’t pay these court-ordered debts, some local officials have not been shy about tossing them in jail, leading to the creation of modern-day “debtor’s prisons” full of poor offenders, advocates say.

“The system doesn’t really work when the courts, instead of administering justice, are debt collection agencies,” said Roopal Patel, co-author of a 2010 report on the issue by the Brennan Center for Justice. “If a court is preoccupied with fundraising and turning toward the poorest people going through the system to raise money, it really undermines the function of the courts.”

While there is no comprehensive data on how many states jail citizens for court-related debt, several organizations, including the Brennan Center, have raised alarms over what they say is the widespread practice of locking up poor offenders in violation of federal law, citing Supreme Court rulings that someone can only be incarcerated for “willfully” refusing to pay.