Providing expert witness for alcohol and positive drugs of abuse test results

Often in judicial trials, employment arbitration or administrative hearings positive drug tests are a factor in the proceedings. In these cases, it is important to consider the validity, or lack of validity, of the drug testing results. An expert witness in these instances is a laboratory professional who has the expertise to render an opinion regarding the validity of test results based on the information provided to them as well as information from the scientific literature. Depending on the situation, the expert's background will be in forensic or workplace drug testing. It is important for the expert witness to be familiar with testing procedures and potential interferences, the various settings where their testimony may occur, possible alternative explanations for positive results and how their testimony may be used. This chapter will discuss venues for expert testimony, provide a description of what an expert witness is, discuss preparation for proceedings where expert testimony is needed and review potential alternative explanations for positive drug test results.