“She at no time gave consent,” Anita M. Rodriguez, the assistant state’s attorney who prosecuted the case, said during Mr. Clinton’s sentencing hearing on Jan. 3, according to a transcript. “In fact, earlier in the evening, she had specifically indicated that she did not want any sexual contact with this defendant.”

Mr. Schnack argued that mandatory sentences take away a judge’s discretion.

“Every individual should be judged by the court in doing its sentence and not by a legislator years and hundreds of miles removed,” he said, according to the transcript.

He also said that prosecutors had not proved their case against Mr. Clinton and that the girl was able to consent. Mr. Schnack said that she made many decisions that night, including drinking and stripping down to her underwear to go swimming.

“They weren’t the best decisions,” he said. “She did know what was going on.”

Judge Adrian said he knew that, by law, Mr. Clinton was supposed to serve time in prison, but in this case, the sentence was unfair, partly because Mr. Clinton turned 18 just two weeks before the party and, until his arrest, had no criminal record.

“That is not just,” Judge Adrian said during the Jan. 3 hearing, according to the transcript. “There is no way for what happened in this case that this teenager should go to the Department of Corrections. I will not do that.”

He said that if he ruled that the sentence was unconstitutional, his decision would be reversed on appeal. Instead, he said, what he could do was “find that the people failed to prove their case.”

Judge Adrian chastised the parents and other adults who he said provided liquor to the teenagers at the party and failed “to exercise their parental responsibilities.”