Because illicit drug use is by definition illegal behavior, patients have learned to be very cautious in what they will divulge about their activities. Thus they often are highly motivated to be dishonest in reporting their substance abuse. Although the vast majority of therapeutic interactions represent privileged communications, drug abusing patients may not understand or trust the extent to which their admissions of drug use will be kept confidential.

To facilitate more open communication and mutual trust, therapists should spell out the nature and limits of confidentiality from the very start. Patients may not be pleased to hear about the limits, but they will appreciate the explanation and the warning. Therapists will need to emphasize that their primary role is to help patients confront their drug use and improve the quality of their lives; therapists do not serve as society's watchdog, or punish, or oppress.