The former chairman of Montgomery County's Republican party was locked up in November.
A grand jury concluded that Kerns offered the woman a ride after she got tipsy at a late October office party.
Prosecutors say Kerns gave the 52-year-old victim wine laced with Ambien, the so called 'date rape drug', and she soon passed out.
The victim testified in court Friday.
"The facts of this case demonstrate a violent rape perpetrated against a defenseless woman," said Samantha Cauffman, Montgomery County Assistant D.A.
The accuser says she remained unconscious for a long time, when the first attack allegedly happened and did not wake until Kerns driving was her home.
She testified that he took her to her bedroom, took some of her clothes off and began to fondle her.
"I knew what was happening but I did not have the where-with-all to do anything about it," she said in court.
Authorities say Kerns then raped her again.
"Traces of Ambien were found in her system about a day after the assault," said Cauffman.
The accuser, whose husband was in Europe, testifies that she woke up the next morning with multiple painful injuries consistent with a sexual attack.
Kerns, through his lawyer, continues to deny the lurid charges.
"Not guilty," is all Brian McMonagle, Kerns' defense attorney, had to say.
Meanwhile, Kerns remains free on bail. If the 66-year-old is convicted, he could spend the rest of his life in prison.
