To make the logistics work, Ms. Ebenstein said her team had to ensure that not only expert witnesses but also the plaintiffs seeking to regain their voting rights had the proper equipment to join the trial. Lawyers sent some of the potential witnesses laptops. They have spent the past week practicing to make sure the hardware, software and internet connections all function.

Marq Mitchell, one of the plaintiffs, worried that his unpredictable internet might falter during the trial. “Hopefully it works,” he said.

Florida voters resoundingly approved Amendment 4, an amendment to the State Constitution, in 2018. It restored the voting rights of people who had committed serious crimes, other than murder or sexual offenses, done their time and completed probation.

Last year, the Republican-controlled legislature passed a bill signed by Gov. Ron DeSantis, also a Republican, requiring the payment of court fines, fees and other financial obligations before a felony sentence could be considered fully completed. Some of the debts amount to tens of thousands of dollars.

Civil rights groups saw the law was as an attempt to suppress voting by those convicted of felonies, especially African-Americans and Hispanics who might support Democrats. Tiny margins often decide major political contests in Florida, the nation’s largest presidential swing state.

Mr. Mitchell, 30, voted for the first time in his life in the presidential primary, held in Florida on March 17, at the start of the coronavirus pandemic. He cast his ballot in person in Fort Lauderdale and brought along his cousin so they could both vote.

“That was great,” Mr. Mitchell said. “I felt extremely empowered, because I understood that I had the ability to determine who would possibly represent our country in a way that I’d never been able to before.”