Over the first several months of 2014, the Florida’s Hillsborough County Sheriff’s Office arrested 15 people on drug charges only to have the Florida state crime lab determine the substances thought to have been drugs in fact were not, reports ProPublica. The arrests had been made by deputies using what are known as chemical field tests — inexpensive kits designed to detect the presence of illegal drugs. A suspected substance is dropped into a pouch of chemicals. The liquid turns a certain color if the substance is, for example, methamphetamine or cocaine. Field tests are used by thousands of law enforcement agencies across the U.S. to bring drug charges and obtain guilty pleas. Many officers appear to receive little or no formal training in the proper use and interpretation of these tests and there are no requirements for them to do so.
It’s hard to say how many police agencies have formal training regimens for field tests. Phoenix controlled-substance officers take a two-day class to be certified and another four hours of training annually to be recertified. A 2011 federal survey of 10 jurisdictions that used field tests found just two provided any kind of formal training. Most, like Hillsborough County, seemingly leave officers to figure out the science on their own. No government agency tracks how often police use field tests, but what little research exists suggests they are ubiquitous. Officers arrest 1.2 million people a year nationwide on low-level drug crimes, many involving evidence derived from the chemical kits.