Police say he smelled of alcohol, staggered and stumbled after they pulled him over for making a turn into the wrong lanes shortly before midnight one night last week.
Todd Haughey, principal of Advantage Academy of Hillsborough charter school, says he had not been drinking but had a bad reaction to medication he was taking.
Either way, the 44-year-old ended up in the Pinellas County Jail early Saturday, charged with misdemeanor driving under the influence.
Haughey spent about seven hours behind bars before being released on his own recognizance.
His troubles began about 11:45 p.m. Friday when he turned his 2007 Pontiac from Central Avenue to go north on 34th Street, said St. Petersburg police spokesman Mike Puetz.
The only problem, the spokesman said, was that he turned his car into the southbound lanes.
Haughey showed signs of impairment including slurred speech and bloodshot and watery eyes, according to the arrest affidavit. He also staggered and stumbled and smelled of alcohol, the arresting officer wrote.
The principal refused to take a breath test that would have analyzed his blood alcohol content, police said.
Haughey said Wednesday he had been at the beach for dinner and had been up since 5 that morning. He said he had been feeling lightheaded and dizzy from medication he had been taking.
He declined to say what the medication was for, but said he had not been drinking at all.
"I'm fighting the charge," said Haughey, who lives on Lemon Street in Tampa. He has hired an attorney.
The principal said he returned to work as normal Monday morning at the school, which has about 500 elementary and middle school students at its campus on Prosser Drive in Plant City.
Charter schools are funded by the Hillsborough County School District but run by private companies. Members of the school's board of directors could not be reached for comment.
The school district has no oversight role of those who work in charter schools, said Linda Cobbe, spokeswoman for the district.
Had Haughey been a district employee, he would not have been suspended in connection with his misdemeanor arrest, Cobbe added.
In 2010, he quit his job as an assistant principal in Manatee County in lieu of being fired, Manatee school officials said.
He had been under investigation after he contacted an ex-girlfriend despite school district officials telling him not to, school officials said.