As voting rights advocacy groups clash with Florida officials in the courts over a law restricting felon voting rights, a preliminary study filed this month presents a staggering estimate of the law’s effect.

In November, voters passed Amendment 4, the ballot measure allowing Floridians (except those convicted of murder or sex offenses) to register to vote as soon as they serve out a felony sentence. But earlier this year, a bill passed by the Republican-controlled state Legislature and signed into law by Gov. Ron DeSantis stipulated that completing such a sentence requires first paying off court fines, fees and restitution.

That would mean thousands of dollars for most felons. According to the preliminary study, fewer than one in five whose voting rights were restored by Amendment 4 have paid everything off.

The study examines records of about 375,000 people — those who live in 48 of Florida’s 67 counties and were released from custody or supervision by Florida’s Department of Corrections. Only about 18 percent of that population — or about 67,000 — showed a zero balance in records from local clerks of court.

“There is little doubt that (Senate Bill) 7066 will severely limit the ability of eligible Floridians with a past felony conviction to be able to register to vote,” wrote the study’s author, University of Florida political science professor Daniel Smith.

Lawyers attached the study as an exhibit in a case against DeSantis and local supervisors of elections. Plaintiffs, including the Florida State Conference of the NAACP and League of Women Voters of Florida, argue the Legislature’s law violate’s the U.S. Constitution’s clause guaranteeing equal protection under the law. They also argue it violates the 24th Amendment, which prohibits the Jim Crow era practice of imposing poll taxes to prevent or discourage African Americans from voting.

There are many more people affected by the law than there are in the sample, which does not include those convicted of federal crimes, for example. Groups have previously estimated more than a million Floridians had their voting rights restored by Amendment 4.

If the results from the study population are true for everyone, that would mean more than 80 percent of people who thought they gained voting rights in the fall had their hopes dashed in the spring.

But the Florida Rights Restoration Coalition, a nonprofit that advocates for “returning citizens” and one of the largest proponents of Amendment 4, felt the estimate was too high.

Asked if the 80 percent rate echoed the group’s experience, Florida Rights Restoration Coalition Political Director Neil Volz said simply, “It doesn’t.”

Part of the reason may be that some outstanding balances are exempt from the law’s requirements. Any costs that “accrue after the date the obligation is ordered as a part of the sentence” are excused, so that someone isn’t barred from voting simply due to interest piling up over time.

Another key finding from the study was a marked disparity between money owed by black people and white people.

The preliminary analysis estimated that the rate of black people who have paid off all financial obligations is “far lower than the comparable rate of white individuals.”

Volz said the disparity was clear in the Florida Rights Restoration Coalition’s “initial look” at statewide data as well.

“There is an undeniable racial disparity in our criminal justice system, and we see that play out through the entire process."

In early July, the group established a campaign to raise money to give directly to certain felons’ outstanding fees. As of Tuesday, about seven weeks later, the group had raised nearly $300,000.