Florida's system of restoring voting rights to people who have committed a crime is riddled with discrimination and bias, including bias in favor of a political party, and violates the U.S. Constitution, lawyers argue in a new brief in a federal court.

The U.S. Court of Appeals for the 11th Circuit in Atlanta will soon hear oral arguments in the case of Hand v. Scott, in which nine convicted felons are challenging the system of restoring felons' rights known as clemency, controlled by Gov Rick Scott and the Florida Cabinet.

In its brief, the Fair Elections Center, a Washington, D.C. voting rights group, says state officials "invoke a variety of ad hoc, shifting, subjective and vague standards and factors: whether the applicant has 'turned [his or her] life around,' has shown sufficient remorse, or has an 'attitude' the board appreciates. Governor Scott has bluntly stated that the process is not constrained by any law."

After reviewing two decades of hearings, the lawyers cited a series of cases in which three governors — Scott, Republican Jeb Bush and Democrat Lawton Chiles — showed partisan political bias in their decisions.

"In 2013, Governor Scott confronted Stephen A. Warner with his illegal voting but then the board granted his restoration application, after he informed them he had voted for Governor Scott," the brief states.

Citing a long line of cases, lawyers argue that voting is a right of political expression protected by the First Amendment, and that giving elected state leaders "unfettered discretion" and "limitless power" to decide if and when convicted felons may vote is a violation of the Constitution.

"For our democracy to stay true to its founding principles," the lawyers argue, "core political expression and association rights must not be arbitrarily licensed or allocated by government officials."

READ MORE: Thousands wait decades to regain their right to vote

U.S. District Judge Mark Walker struck down the restoration process in February but Scott and the Cabinet won a stay of Walker's order from a three-judge panel in April. Oral arguments are set for July 25.

Scott and Cabinet members meet once every three months to decide whether to restore applicants' rights. The other members are Attorney General Pam Bondi, Chief Financial Officer Jimmy Patronis and Agriculture Commissioner Adam Putnam.

Felons cannot apply for restoration of rights for at least five years after completing their sentences. The state has a backlog of more than 10,000 clemency applications.

As Scott said at the most recent meeting on June 14: "Clemency is an act of mercy. You have no right or guarantee of clemency. Our decisions are based on many facts and circumstances. While courts may make judgments in law, our clemency board makes judgments of conscience based on the suitability of each applicant to be granted clemency."

As the case works its way through the federal courts, Florida voters will also have their say on the issue this fall.

Amendment 4 on the November ballot will ask voters to change the state Constitution, to automatically restore the right to vote to most convicted felons after they have completed all terms of their sentences. The change would not apply to people convicted of murder or felony sex offenses.