States all over the country are being sued by civil rights groups for aggressive debt collection by their courts. This has led to much discussion of what is being called a new debtor's prison system in the US, and also to some confusion.
Technically, you cannot go to jail for failure to pay a civil fine, like a loan. But in some states where consumer protections are not very strong, creditors can ensnare debtors in the court system. Failure to appear for hearings or otherwise respond to court orders arising from collections cases can result in warrants, jail time, and fines. The punishment is for disobeying court orders but the trouble still stems from an unpaid debt.