The narcotic contract
 

When patients come to you who are already taking narcotics for chronic pain, it may be unclear that substance abuse is a significant problem. For these patients, it is helpful to be explicit about the circumstances under which you will prescribe narcotics. Asking your patient to sign a narcotic contract can be very helpful.

The NIDA Centers of Excellence for Physician Information (CoE) http://www.nida.nih.gov/coe/coe.htm provide, amongst many other valuable resources, an example of a narcotic contract on page 8 - 9 of http://www.nida.nih.gov/coe/pdf/preventing-supporting-docs.pdf (provided by Boston University School of Medicine).

In the video on the next page, you can observe Dr. Parran discussing a narcotic contract with a patient.