Police said Widmer told them she did not know how to change a flat, so they asked her to pull into a parking lot so they could help. Officers said she activated her left-turn signal but attempted a right-hand turn onto a grassy area before stopping in the middle of the lot.
Widmer smelled strongly of alcohol, said police, who noted that she failed a field sobriety test.
Officers arrested her and said they found a bottle of vodka in the center console of her vehicle. Widmer was charged with operating a vehicle while intoxicated and possession of an open container.
Her son is to stand trial in January for a third time in the drowning of his wife, 24-year-old Sarah Widmer.
His April 2009 conviction and life sentenced were overturned because of juror misconduct. A second trial in June 2010 ended when the jury failed to reach a unanimous verdict.