Diaz, 49, is accused of punching the pair after the other motorist honked his horn when the attorney's car blocked the entrance to a supermarket parking garage last Dec. 18, according to a Miami police report (pdf).
Arraignment is set April 5 in Miami-Dade Circuit Court for Diaz, who was charged with two felony counts of burglary with assault and battery and two misdemeanor counts of battery.
A personal injury lawsuit has been filed by the driver, financial analyst James Bracco, 30, against Diaz in civil court.
Diaz referred calls to his attorney. Diaz's attorney, Joseph Rosenbaum, contends his client was attacked, not the other way around.
"Mr. Diaz defended himself and the others with him that evening. There are several eyewitnesses who will corroborate these facts and completely exonerate Mr. Diaz from any wrongdoing," he wrote in an e-mail Thursday.
The incident occurred on a Friday night when Bracco and Nancie Grace George, 23, set out to shop at a Publix store near his condo before a movie night.
When they reached the garage, a Lexus blocked the entrance, the police report said. Several cars in line honked at the stopped car. Bracco yelled out his window at Diaz when he finally drove by the Lexus.
Diaz then stormed out of his car, pulled open Bracco's door and punched him several times in the face, the report said. Diaz dragged Bracco out of the car, slammed him against it and continued punching him. When George tried to stop the fight, Diaz punched her twice in the chest. Police reported Bracco was bleeding from his nose and mouth.
Diaz made no statements, "but he emitted a strong odor of alcohol out of his breath," the police report said. He was given a citation to appear in court.
Bracco said he spent Christmas with a black eye and busted front teeth, which required a plastic splint to keep in place -- one he still wears three months later.
"I couldn't chew for well over a week," he said.
Misdemeanor charges were filed against Diaz on Jan. 4.
Bracco hired Miami personal injury attorney Justin C. Leto, who filed a civil lawsuit in January. Miami-Dade Circuit Judge Gisela Cardonne Ely granted a motion by Diaz's civil attorney Peter Restani of Restani Dittmar & Hauser to keep Diaz from giving a civil deposition before the criminal case ends. Leto has appealed to the 3rd District Court of Appeal.
Rosenbaum dismissed the civil suit as "nothing more than an unscrupulous attempt to extort a financial resolution from a frivolous civil suit."
But the state attorney's office raised the stakes in Diaz's criminal case by adding felony charges March 15 after reviewing the arrest forms and interviewing witnesses.
Ed Griffith, spokesman for the state attorney's office, offered an explanation for the lag time of almost three months between the incident and the filing of felony charges.
"By issuing a promise to appear, it did not immediately come to the attention of the prosecuting attorneys," he said.
Diaz's firm, which has offices in Latin America, Europe and Asia, handles business and financial cases for international banks, Fortune 500 corporations and foreign governments. Diaz, a University of Miami law school graduate, lectures about finance and law around the world. His latest speaking engagement was at a business fraud conference in Mexico City this month.