Presumptive Specificity: Examining the Duquenois-Levine Field Test for Marijuana

Practitioners who have handled cases involving marijuana are likely to be familiar with the Duquenois-Levine field test.  As of 2008, the NIK NarcoPouch 908 was the most commonly used marijuana field testing kit utilizing the Duquenois-Levine Reagent.  However, despite its wide use, forensic drug expert John Kelly stated in a 2008 report to the California Attorneys for Criminal Justice (CACJ) that there were no published studies examining the validity of the field test.  Kelly’s report, which was written pursuant to one such study, criticizes the Duquenois-Levine field test as being non-specific and rendering false positives, which he asserts violate Supreme Court rulings and undermines the integrity of tens of thousands of marijuana convictions.