Roadside Drug Tests Routinely Produce False Positives, ProPublica Reports


Every year, tens of thousands of people are sent to jail based on the results of an unreliable, $2 drug test, a ProPublica investigation found.

In an investigative report published this month, ProPublica details the problems with field tests which, despite their widely acknowledged unreliability, nonetheless provide the sole evidence for tens of thousands of drug convictions in America each year.

The field test kit was patented in 1973, the same year that President Richard Nixon established the Drug Enforcement Agency to wage “all-out global war on the drug menace.”

Today, at least nine companies sell tests to identify cocaine, heroin, marijuana, methamphetamine, LSD, MDMA and more than two dozen other drugs. The tests contain a chemical that turns blue when exposed to the illegal substance, but it also turns blue when exposed to dozens of other compounds, including household cleaners. Extreme cold or heat, variations in lighting, and poor instructions and training for officers contribute to false positives, ProPublica reports.

There are no established error rates for the field tests, but authorities in Las Vegas found 33 percent of cocaine field tests between 2010 and 2013 were false positives, and Florida data shows a 21 percent error rate there. No central agency regulates the tests’ manufacture or sale, and no comprehensive records track the use of these tests. In nearly every jurisdiction reporters examined, field tests are not admissible at trial, where prosecutors must instead present evidence from more reliable lab tests.

But that prohibition is essentially meaningless, because as ProPublica reports, at least 90 percent of drug convictions are the result of guilty pleas, and prosecutors and judges in nearly every jurisdiction accept plea deals based solely on the results of field tests.

Given the scale of the war on drugs, the consequences of false positive field tests are staggering. ProPublica estimates that “every year at least 100,000 people nationwide plead guilty to drug-possession charges that rely on field-test results as evidence.”

The majority of crime labs do not test drug evidence after the defendant pleads guilty, but after a series of devastating scandals, the crime lab in Houston, Texas, decided to analyze all field test samples, even years after the arrest. This testing revealed 251 cases between 2004 and 2015 that ended in guilty pleas where there was no controlled substance present. ProPublica determined that 74 percent of people convicted of illegal drug possession did not possess any drugs at the time of their arrest.

Nearly 60 percent of those wrongfully convicted in Houston, which is 24 percent Black, are African Americans. Nearly all of the wrongfully convicted (93 percent) received a jail or prison sentence, including a substantial number who were legally entitled to probation. A majority were wrongfully convicted in their early 20s and 30s, burdened with criminal convictions that limited educational, job, and housing opportunities for years. In fact, ProPublica found that most spent at least seven years saddled with wrongful convictions, and scores of them still have not been exonerated.

The Harris County District Attorney’s office is one of the few nationwide that has a conviction integrity unit, and that unit has cleared 119 wrongful drug convictions in the past two years. But at least 172 have yet to be overturned.

As ProPublica’s investigation makes clear, extrapolating from the Houston experience shows that “tens of thousands of Americans[‘] . . . lives have been torn apart by a very flawed test.”