When former Montgomery County Republican Chairman Robert J. Kerns goes to trial next week on sex charges, he will have to convince only one person of his innocence.

John L. Braxton, a Philadelphia senior judge, was assigned to the case after the Montgomery County bench was recused to avoid any potential bias for or against the onetime political heavyweight.

Court documents show that Kerns, 67, has opted not to take his case before a jury, a strategy one criminal defense expert said could be risky.

"With a jury, the prosecution has to convince 12 people to find guilt beyond a reasonable doubt," said Judith L. Ritter, a law professor at Widener University. "Most defenses would think long and hard about recommending that."

Kerns' attorney could not be reached for comment Tuesday.

In a bench trial scheduled to begin Monday, Braxton will decide whether Kerns is guilty of aggravated indecent assault and penetration of an unconscious person.

Kerns is accused of having nonconsensual sex with an employee of his Lansdale law firm while she was passed out after a night of drinking in October 2013.

More serious charges against him - rape and sexual assault - were dismissed in June by a lower court.

Ritter said defense attorneys might opt for a bench trial if they believed the case hinged more on a technical legal definition or element of a crime, as opposed to a question of facts. Also, for highly emotional crimes, such as child molestation, she said, "there may be a fear [the jurors] won't be able to get past the sympathy for victim or victims."

A spokeswoman for the state Attorney General's Office said she could not comment on the case. Under Pennsylvania law, the defense can only obtain a bench trial if prosecutors agree.

When the allegations went public last fall - in a grand jury indictment - Kerns resigned as GOP chairman and left his law firm.

Kerns, through his attorney, has denied that any sexual assault took place.

The case stalled in March after Montgomery County District Attorney Risa Vetri Ferman acknowledged that her office had misread a lab report and wrongly charged Kerns with intentionally drugging the woman before raping her.

Ferman said she stood by the allegations, but had to drop the case because of the error.

State prosecutors filed charges six weeks later.

The alleged victim, an employee of Kerns' firm, testified at Kerns' first arraignment in December. She said she was celebrating with coworkers at a Blue Bell restaurant, where Kerns bought the woman several drinks, then offered to drive her to the King of Prussia mall.

Once she was in his car, the woman testified, Kerns gave her wine and then assaulted her - once in the car and once in her house after he had driven her home.

It was unclear whether the woman or Kerns will testify during the trial phase. The Inquirer does not identify victims of alleged sexual assaults.

Ritter said the elimination of the jury should make the trial simpler and faster.

"Choosing a jury," she said, "may take as much time as the trial in a case like this."