It is common for a statutory BAC (blood alcohol content) level to determine whether the operator of a motor vehicle is guilty of Driving Under the Influence (DUI, which in some states is called DWI for "Driving While Intoxicated").
My question is: Do any states have a provision in law for interpolating a suspect's BAC backwards in time? It is known that alcohol is metabolized over time. I am wondering if a lower threshold on that metabolic rate has been codified anywhere in law.
E.g., suppose (as is the case in many jurisdictions) that the statutory BAC threshold for DUI is 0.08%: If a suspect is measured to have a BAC of 0.07%, but is known to have been driving at some point in time prior to the measurement, how (if at all) do any jurisdictions allow the suspect's BAC to be interpolated to the earlier point in time?
For example, there may be some significant delay between when a suspect is observed driving and when the suspect's BAC can be assessed with a legally sufficient test. During that time the suspect's BAC continues to decrease through alcohol metabolism. Given enough of a delay, a suspect who was in fact operating with BAC over the legal limit may end up showing a BAC under the legal limit when finally tested. Do any jurisdictions allow the state to account for that delay to assert that the BAC while operating the vehicle was higher than the level read by the test?