The question is intent. Purposely taking a sleeping medication is not a crime. She was not charged with that.
Driving under the influence of a medication is a crime. She admits that she did that, but that it was an accident and not her intent. The jury believed her (fair enough) and acquitted her of drugged driving.
But I wouldn’t try an “I didn’t intend to get drunk at Happy Hour” defense if you get popped for DUI.
That's right, but she was declared not guilty of 'intent'! That could work for any crime with an O.J. jury like this one.