ATLANTA -- College student Casey Metcalf received a citation for riding alone in an HOV lane. She said she had no idea it was one. When she didn’t have all the money to pay the fine, she had no idea she’d end up in jail.

“I was in shock. I was in complete shock,” said Metcalf.

Metcalf was in shock when in less than 45 seconds, Atlanta Municipal Court Judge Elaine Carlisle sentenced her to five days in jail. Her offense? Not having the money to pay an HOV lane violation fine.

“I just thought it was awful and completely ridiculous that I was going to jail for this,” said Metcalf.

The courtroom video showed Judge Carlisle first sentencing Metcalf to a year in jail.

After Metcalf pleaded guilty to driving in the HOV lane as a single occupant, the judge said, “The prosecuting attorney is recommending a baseline of $75 and with all of the state required surcharges that actually comes to a fine $119.25. I'm imposing 1 year in jail, which will be suspended upon payment of the fine. Are you prepared to pay the fine in full immediately?”

Metcalf said no. The judge then asked her if she was employed and Metcalf responds in court, “I’m a graduating senior in college.” That’s when Judge Carlisle says, “OK. Then unfortunately I can't place you in the probation program. I'm going to impose five days in jail. Someone will have to pay that for you before you can be released. You need to step over here.”

Metcalf spent about six hours in jail until her sister paid the fine. What Metcalf didn’t know is the judge had no right to put her in jail.

“That was an illegal sentence,” said attorney Mazi Mazloom. Mazloom said the law is clear. A $75 fine is the maximum punishment for a first offense HOV violation. “Not five days. Not five minutes. Not five seconds in jail,” said Mazloom.

Atlanta’s solicitor general agrees Metcalf shouldn’t have been locked up.

“I can’t explain it. The statute clearly says for a first offence, $75,” said Atlanta Solicitor General Raines Carter.

Channel 2’s Tom Jones reached Judge Carlisle by phone. She didn't want to talk on camera and told him our camera wasn't allowed in her courtroom. She did admit she never should have sentenced Metcalf to jail time when she couldn't pay her fine.

Carlisle told Jones she misinterpreted the law and didn’t realize the violation is a fine-only offense.

“I don’t want an HOV lane arrest on my record,” said Metcalf.

The college senior said she wonders how a judge could make such a mistake. “I think it’s appalling,” said Metcalf. “I have no idea how many other people this has happened to.”

A motion has been filed to set aside Metcalf’s conviction and get it off her record. No court date has been set yet.