Another risk for wrongful conviction is law enforcement’s use of color-based field drug tests. These are “presumptive” drug kits, often used during roadside stops, that are used to attempt to determine if a given substance is a narcotic. The problem is that these color-based field tests are not reliable. They have identified household items like folic acid, jolly ranchers, soap, and cat litter as illegal drugs. Because of the unreliability of color-based presumptive field tests, substances that test positive are supposed to be sent to a crime lab for a more reliable test to confirm whether it is actually a narcotic. Unfortunately, that rarely happens. Why is that? Because most people, facing detention, the loss of their jobs, housing or custody, will understandably plead guilty to avoid these issues and end up with a permanent conviction on their records. And who is affected most frequently? People of color arrested for low-level drug offenses.
Police agencies, if they currently use presumptive color-based field drug tests, should stop using them, as the Houston Police Department did following the revelation of more than 100 wrongful drug arrests based on these tests.
If a police department is going to use these presumptive tests, then they must take other steps so that a conviction is not entered before a crime lab has tested the substance and confirmed the test result. To prevent innocent people from pleading guilty in the face of a positive presumptive field drug test, police should never detain people during the period of time between a presumptive field drug test and confirmatory lab test.