According to MVA records, Phelps has not received any driving infractions in Maryland in the last three years. An MVA official said Phelps' record could also be clean elsewhere because other states routinely share information with Maryland.
Phelps could receive a six-month license suspension. In such cases, the MVA would send a letter notifying of the possible suspension, which can be appealed, said the agency's spokesman, Buel Young.
Failing to take a blood-alcohol test could also result in a license suspension, Young said.
If found guilty as a first-time offender of the most serious charge he faces, driving under the influence, Phelps would be subject to anything from probation before judgment to a year in jail, a $1,000 fine and 12 points on his driver's license. Driving while impaired carries a maximum penalty of 60 days in jail, a $500 fine and eight points for a first offense.
Judges weigh in
Depending on the judge, he could also be ordered to abide by probationary conditions like community service or attendance at a MADD victim impact panel or Alcoholics Anonymous meetings.
Two judges, who spoke generally about drunken-driving cases, said they look at a variety of factors when deciding on an appropriate punishment for a first-time drunken-driving offender - including prior infractions and age.
Chief District Court Judge James N. Vaughan said underage violators "carry a burden" in his court because they've already broken the law just by drinking.
Whether an offender has caused an accident and whether he or she has an alcohol problem also go into the mix.
"What, if any, alcohol dependency is important because I want to know, `What is the likelihood of future danger to the public?'" said Judge Keith E. Mathews, the administrative judge for Baltimore District Court.
Yesterday, Phelps' fans continued to weigh in, some on an unofficial fan site where hundreds of people posted reactions.
"I'm still a huge fan, but I didn't think he would do something so utterly stupid," one 13-year-old wrote. "I mean[,] fine[,] drink, even though I don't think he should since he's underage, but don't drive."
Sun staff writers Matthew Dolan, Molly Knight, Jennifer McMenamin, Chris Guy and Joe Nawrozki contributed to this article.