From the module, "The clearly established relationship between blood alcohol and accidents has led to most jurisdictions adopting the so-called per se law in which a blood alcohol over a stated level is taken as evidence of intoxication. The traditionally accepted level is 0.100% (0.1g/100 ml) or 0.08 depending on the state. The per se law is regardless of the defendant's field sobriety test, breath test or tolerance to alcohol. If the 0.10 or 0.08 level can be proved - it creates an irrefutable presumption of guilt. This also means that BAC data and methodology is frequently challenged in court."

Some states' laws don't mandate the quantitation of drugs (other than alcohol) in "under influence" cases. With so many different levels of influence at many concentrations, all of which varies from person to person, it would be almost impossible to prove influence, or to set limits for all drugs.

Trained specialists known as Drug Recognition Experts (DRE) observe a suspect and report on the drug the DRE suspects the individual is under the influence of. If the lab confirms the presence of that drug, the DRE report and lab report are used in court to prove influence. This eliminates the need to show concentration due to the DRE showing that the individual presented signs of influence, with subsequent drug presence confirmed.

Discuss the use of the DRE observation along with a lab confirmation to prove influence as opposed to lab confirmation with quantitation. Should we perform a quantitation on all drugs in influence cases instead of just confirming or is a DRE exam and lab confirmation good enough to call someone "under the influence"? Why or Why not?