B.J. Bernstein told Monroe County Superior Court Judge Thomas Wilson that the Georgia Legislature changed the law in 2006 so that Mr. Wilson would be treated far less severely if he committed the same offense now. The sentence, she said, is "grossly disproportionate."
"It gets back to common sense," Ms. Bernstein said. "This very act is only a misdemeanor with no sex offender registration today.
"We are asking this court to void this sentence. We are asking this court to release Genarlow Wilson," she said.
But a lawyer for the state told the judge that the conviction should stand and Mr. Wilson should remain behind bars.
Senior Assistant Attorney General Paula Smith acknowledged that lawmakers had changed the law. But she said the state's top court had already held that the new law could not be applied retroactively.
"That is the bottom line. The General Assembly did not make it retroactive," Ms. Smith said. "They had the prerogative to do so; they did not."
The judge said he would rule Monday in the high-profile case, which drew a pack of reporters and television cameras to the tiny Monroe County Courthouse.
Mr. Wilson appeared in the courtroom on Wednesday, clad in a white prison uniform.
Now 21, Mr. Wilson is serving 10 years without the possibility of parole after a jury found him guilty in 2005 of aggravated child molestation for having consensual oral sex with a 15-year-old girl during a 2003 New Year's Eve party involving alcohol and marijuana.
He was charged with rape for being one of several male partygoers to have sex with a 17-year-old girl, but was acquitted. The party was captured on a videotape that was played for the jury.
Several influential people, including former President Jimmy Carter, have stepped forward to support Mr. Wilson. Mr. Carter, citing the "disproportionate nature" of the punishment, questioned whether a white teen would have faced a similar sentence.
"The racial dimension of the case is likewise hard to ignore and perhaps unfortunately has had an impact on the final outcome of the case," Mr. Carter wrote to state Attorney General Thurbert Baker in a May 24 letter supporting the man's petition.
"There is some statistical evidence reported by various nonprofit agencies in Georgia, leading me to believe that white minor defendants in the same circumstances as Mr. Wilson's receive far lesser forms of punishment," Mr. Carter wrote.
If Mr. Wilson had had sexual intercourse with the 15-year-old he would have fallen under Georgia's "Romeo and Juliet" exception with the maximum penalty being a year in prison.
But under the law in 2003, oral sex between teens constituted aggravated child molestation, carrying a mandatory sentence. It also required registering as a sex offender.