I have heard stories that people have left the scene of an accident, allegedly gone home, allegedly had a beer and returned to the scene (with a driver) where police have not charged them with a hit-and-run because they showed back up and, further, were prevented from administering a sobriety test because of the admission or having alcohol (when they are no longer driving.) I would suggest further amending this law to state that after such an accident, no one involved shall be allowed to consume any substance that would invalidate a DUI test. Consumption of such a substance would be assumed to have been taken prior to the accident and that any test for driving under the influence would be legally assumed to be valid.
I would hope that if someone hit me and actually stopped but popped his trunk, took out and consumed a beer, while awaiting the arrival of law enforcement could not avoid a conviction for impaired driving.