Abstract: A non-invasive screening system and method for suspected drug users includes computer software, which when executed displays a series of categories each listing one or more physical elements capable of being observed by a trained operator. Partial categories include ATTITUDE, SPEECH and ODOR and exemplary elements thereunder comprise (1)sedated, euphoric, irritable; (2)deliberate, sluggish, repetitive; (3)alcohol, chemical, glue, respectively. As the various categories and their physical elements are displayed among various menus presented on a computer monitor, the operator tags only those elements which are observed to exist in the suspect. When all menus have been responded to by the operator, the software notes which elements of each category have been tagged and with this data at hand, applied weights to the responses in accordance with a database history of which elements are most contributory to a positive conclusion with respect to each of a plurality of drug classes.