How Drug OUI / DUI Differs from Alcohol DUI

Drug DUI's are substantially different from alcohol DUI's in the evidence the Prosecution will use to assess intoxication. Specifically there is no test that demonstrates intoxication from drugs. Even if the police had a blood or urine sample that showed the presence of an intoxicating drug, this is not dispositive evidence of intoxication. Unlike alcohol, people test positive for many drugs LONG after the intoxicating effects have worn off. As such, there is no effective test to scientifically measure drug intoxication.

Drug Recognition Experts (DRE)

As there are no scientific tests for Drug DUI, the Prosecution must instead rely of observations of the Defendants behavior and physiological signs in order to prove intoxication. The person who conducts this exam is known as a Drug Recognition Expert, commonly referred to as a DRE. These are not doctors. Normally they will have no substantial training in biology or chemistry. Rather these are Police Officers who have undergone training to recognize the signs of drug intoxication. As such, there conclusion, which may be based on observations, isn't so much scientific fact as it is subjective opinon. In my experience the best way to combat this is with an expert witness who has actual expertise in the field of intoxicating substances, and other conditions that mimic those symptoms.

Drugs that are Legal - Marijuana and Prescriptions

A question that continually comes up is: what if I took a drug but it was legal? This question is asked, most commonly, in reference to marijuana (now legal in the commonwealth) and legally prescribed drugs.
The quick answer is that one can be guilty of DUI by ingesting legal or illegal substances. The example I give is always the same: I am over 21 years of age, it is perfectly legal for me to drink all I want, but my conduct becomes illegal if I starts driving afterwards.