In an update issued by the Montgomery County District Attorney's Office, Keough pleaded guilty to the misdemeanor charge on Wednesday.
The charge stems from a crash that happened on Sept. 10, 2020. Keough was behind the wheel when his SUV sideswiped another driver, and then rear-ended a deputy constable's patrol vehicle, according to court documents.
He said Ambien was found in his blood stream after the crash.
"There was not any alcohol involved in this at all, but rather what they found in my blood was a doctor's prescribed sleep aid called Ambien," explained the judge in a video published to his Facebook page. "Now, what I did not understand at the time is that this can have lingering effects. Sleep aids, in general, can have lingering effects the next day, but the fact of the matter is my motivation, or how I did it or where I got it from, is not a defense to prosecution. I got up, I went to work, just as usual, but I didn't expect it to end this way. Sure enough, it resulted in this DWI. I've given this a lot of thought and I take responsibility for that. The fact of the matter is ... they found it in my blood stream."
READ MORE: Montgomery Co. Judge Mark Keough turns himself in for DWI charge
For his sentence, Keough's driver's license was ordered suspended for 90 days, and he was required to pay a $2,000 fine.
He will also be required to pay court fees.
"Like many citizens of Montgomery County in a similar situation, Mr. Keough, through his plea of guilty, has accepted responsibility for the charge," read a statement from the district attorney's office. "This plea resolves any criminal responsibility for the events surrounding the automobile crash of September 10, 2020."
Meanwhile, the man hit by Keough told Eyewitness News he had to get special treatment for spinal injuries he suffered as a result of the accident.
"I haven't been the same since that accident. I got rear-ended. There's an abnormal spine," he said.
READ MORE: Man hit by Montgomery County judge says he hasn't been the same since crash