Drug testing is helpful (even indispensible) as a way of motivating
drug and alcohol dependent people to remain clean and sober. Drug and
alcohol dependent people are often in denial about the nature and
extent of their problems and typically do not want (wholeheartedly) to
quit, at least the first time or two they enter treatment. They often
lie about their substance use, either denying that they have used at
all, or minimizing the amount of drugs or alcohohl that they have used.
It is necessary to obtain objective and indisputable evidence of
whether or not a drug and alcohol dependent person is using drugs or
alcohol during the early and middle phases of treatment.
Most drug tests ('screens') are performed on urine samples that
drug dependent persons must provide twice a week (the detection limit
for many drugs being about three days in length). In addition to urine sampling, drug testing may occur variously by way of breath tests, or sampling of blood, hair, saliva and sweat. Ideally, urine (or other body substance being sampled) is collected with a clinical worker present in the bathroom (so
as to verify that the urine presented in the sample is in fact from the
body of the drug dependent person and not from a plastic bag they have
carried, and that the urine is not adulterated in any way). Some drug or alcohol dependent people are in such
denial that they will maintain that they have not used, even when test
results clearly indicate that they have used drugs or alcohol, so it is
helpful for clinicians to set an up front treatment policy that drug
test results will be believed over the word of drug dependent persons
when there is any question of use.