Cash-strapped states are increasingly imposing a number of fees on poor criminal defendants, including fees for a public defender, according to a report by the Brennan Center for Justice, a nonpartisan policy and law institute affiliated with New York University’s Law School.

The report (PDF) found that of the 15 states with the largest prison populations, 13 allow low-income defendants to be charged fees for exercising their right to counsel. Some states even mandate these fees, meaning the court can’t waive the fee for even the poorest of defendants. In two states — Florida and Ohio —  individuals must pay defender fees even if they are acquitted or charges are dropped.

While these fees are used to boost revenue to the criminal justice system, their imposition raises “serious constitutional questions,” according to the report, which noted that the fees “often discourage individuals from exercising their constitutional right to an attorney — leading to wrongful convictions, over-incarceration, and significant burdens on the operation of courts.” These defender fees can come in several ways:

Defender fees can include charges to “apply” for representation before an attorney is appointed, charges during the course of a criminal proceeding to offset the costs of representation, and charges at the termination of a criminal proceeding to reimburse the state for all or a portion of the costs of representation.

But defender fees are just one of a number of the fees courts may impose on defendants throughout a criminal proceeding. Other fees states imposed included jail fees for incarceration prior to trial, prosecution reimbursement fees, prison fees, fees for court administrative costs, probation and parole fees, drug testing fees and mandatory treatment fees, in addition to fines dealt simply as punishment. Often, the fees continue to stack up when defendants are unable to pay off their criminal justice debts, or make their payments late.

“Every stage of the criminal justice process, it seems, has become ripe for a surcharge,” the report said. Many states deny ex-convicts voting or driving privileges if they miss payments or have not paid off such debt.

Not everyone thinks these fees are unfair. Jim Reams, president of the National District Attorneys Association, told USA Today that most criminal defendants don’t serve time and receive some form of probation, so “their job status and economics can and should change relatively quickly,” allowing them to pay off their debts.