In what the defense and prosecution agreed was a rare decision, a Chester County Court judge has thrown out an aggravated-assault conviction against a man found guilty of beating his girlfriend.

It marked the first time in decades that a judge has overruled a jury's verdict in the county, according to District Attorney Tom Hogan.

"One of the bedrock principles of criminal law is that a jury's verdict is not to be disturbed," said Hogan, who has said he will appeal if Senior Judge Ronald Nagle does not change course.

Nagle, who acted on a defense motion and reversed the conviction against Michael Ferko on Friday, citing insufficient evidence, did not respond to an interview request. The District Attorney's Office said it was not given details of the judge's reasoning.

First Assistant Public Defender Nathan Schenker, whose office represented Ferko, defended the judge's decision.

While they are rarely granted, Schenker said, motions for acquittal are commonly made when a defense attorney feels there is not sufficient evidence for a guilty verdict.

"We certainly are very supportive and believe the jury system is very important," he said. "But there is a reason why we have this state rule that allows the judge to find that the sufficiency of the evidence has not been proven."

Said Theodore Simon, a Philadelphia lawyer who is president-elect of the National Association of Criminal Defense Lawyers: "The granting of a post-verdict motion, while infrequent, remains a necessary and important judicial protection against wrongful convictions."

Under the state's "three-strikes" law, Ferko faced a mandatory 25- to-50-year prison sentence because he has twice been convicted of violent assaults. Hogan, noting that both those assaults were against women Ferko was dating, said he "richly earned the sentence he was about to get."

Ferko is awaiting sentencing for the other crimes he was found guilty of at the Dec. 4 trial: misdemeanor simple assault and making terroristic threats.

Ferko has an long criminal history dating to 1980: driving under-the influence, drug possession, and multiple harassment and assault convictions.

Deputy District Attorney Thomas Ost-Prisco, who prosecuted the case, said Ferko was convicted in 1981 of threatening to kill a woman if she did not have sex with him and, in 1996, of beating a woman.

The prosecutor said that in the current case, Ferko choked a woman, fractured her rib, and ruptured her eardrum. Ost-Prisco said that during the trial, Ferko did not dispute those facts, but said the attack constituted simple assault, not aggravated assault. The jury disagreed.