Martin Luther King III (L) waits to place a wreath at his fathers statue during a wreath laying ceremony at the Martin Luther King Jr. memorial on the National Mall January 15, 2012 in Washington, DC. (Photo by Brendan Smialowski/Getty Images)

Martin Luther King III, along with other supporters of Marissa Alexander, the 30-year-old mother of three who was sentenced to 20 years in prison for firing a warning shot in her home to fend off an attack form her husband, will hold a rally for her in Jacksonville Florida on Friday.

The Jacksonville chapter of the NAACP, clergy, politicians, and community leaders along with King, will March on Friday July 13th to the new Duval County Courthouse in Jacksonville, to call attention to the application of mandatory minimum sentencing and Alexander’s case.

Alexander rejected a three-year plea deal, believing the circumstances of her case fit the guidelines of Florida’s “Stand Your Ground” laws. Rico Gray, Alexander’s husband, whom she was defending herself against the night she fired the warning shot, admitted in a sworn deposition that he had been violent with her at least four or five times in the past.

Although there was a history of violence and no one was hurt from the warning shot Alexander fired into the ceiling of the couple’s home, the jury came back with a guilty verdict.

Isaiah Rumlin, president of the NAACP’s Jacksonville branch, released a statement calling the sentence a gross miscarriage of justice. “Florida’s unjust Criminal Justice System has repeatedly and disproportionately affected minorities. When Marissa Alexander, a repeat victim of domestic violence was sentenced to 20 years in jail for protecting her life. The 10-20-Life and Stand Your Ground Laws have not been consistently applied and we are sending a message that this will no longer be tolerated in our communities.”

Follow Caryn Freeman on Twitter.