War on Drugs

Study Estimates Roadside Drug Tests Result in 30,000 Wrongful Arrests Every Year

Despite the well-known problems with the kits, they're used in half of the roughly 1.5 million drug arrests in this country every year.


Roughly 30,000 people every year may be getting wrongfully arrested and jailed because of police departments' widespread use of unreliable roadside field tests for drugs, according to a study released today by the Quattrone Center for the Fair Administration of Justice at the University of Pennsylvania.

The study, which bills itself as the first comprehensive analysis of the use of presumptive drug field test kits by law enforcement agencies in the country, estimates that each year approximately 773,000 drug-related arrests involve the use of such test kits. That's half of the roughly 1.5 million annual drug arrests in the U.S.

These inexpensive field tests use color reactions to indicate the presence of compounds found in certain drugs. However, the well-documented problem is that the compounds these kits test for are not exclusive to illicit drugs and are, in fact, found in dozens of legal substances. Over the years, officers have arrested and jailed innocent people after drug field kits returned presumptive positive results on bird poop, donut glaze, cotton candy, and sand from inside a stress ball. The Jacksonville Sheriff's Office in Florida stopped using test kits this September after discovering that several common over-the-counter cold medications returned false positives for cocaine. A 2018 investigation by a Georgia news station found that one brand of test kit produced 145 false positives in the state in one year. 

But no one has ever tried to quantify exactly how many innocent people are jailed because of these tests, until now. 

Although the true error rate of these kits is not known, the Quattrone Center estimates, based on the incomplete data it could glean from state drug labs and other sources, that as many as 30,000 innocent people a year may be wrongly arrested for drug possession based on their results, making these tests "one of the largest, if not the largest, known contributing factor to wrongful arrests and convictions in the United States."

"Presumptive field drug test kits are known to produce 'false positive' errors and were never designed or intended to provide conclusive evidence of the presence of drugs," Ross Miller, Quattrone Center assistant director and lead author of the report, said in a press release. "But in our criminal legal system, where plea bargaining is the norm and actual fact-finding by trial is exceedingly rare, these error-prone tests have become de facto determinants of guilt in a substantial share of criminal cases in the United States and, as a result, a significant cause of wrongful convictions."

The Quattrone Center report also found that police departments and local prosecutors' offices often had few policies in place to safeguard against wrongful arrests and convictions based on faulty field tests.

The center's survey of prosecutor offices found that 89 percent of them allow guilty pleas to be entered without confirmatory testing of test kit results, and nearly 70 percent of drug labs in the U.S. reported that they were not asked to review samples when a plea agreement has been reached.

The danger of innocent people confessing to drug possession—often under threat of more serious charges from prosecutors—is not hypothetical. A 2016 ProPublica/New York Times investigation found that 212 people pleaded guilty between January 2004 and June 2015 to drug possession based on Houston Police Department field tests that were later invalidated by crime labs.

Reason reported in 2021 on how these tests are also used extensively in prison systems across the country to punish inmates, despite clear warnings from the manufacturers that the results should be confirmed by outside labs. 

In 2020, the New York Department of Corrections and Community Supervision suspended the use of NARK II test kits for contraband because of reliability concerns. A New York State Inspector General report released last November found that reliance on unverified test kits resulted in 2,000 innocent inmates being unfairly punished—including being thrown in solitary confinement, having visitation rights suspended, and parole hearings canceled.

In 2021, a Massachusetts judge ordered the state prison system to stop using similar field tests, finding that they were "highly unreliable" and "only marginally better than a coin-flip." That suit followed claims by over a dozen Massachusetts attorneys who said they were falsely accused of sending drugs to their incarcerated clients.

And last September, a class-action lawsuit was filed against the Washington State prison system for similarly disciplining inmates based on unverified test kit results.

Among the Quattrone Center's recommendations for reducing the risk of wrongful arrests and convictions are limiting the use of colorimetric tests, requiring confirmatory testing when a guilty plea is accepted, and requiring regular blind audits of cases involving test kits to establish reliable false-positive rates.

"Every year, tens of thousands of innocent Americans are arrested on the basis of $2.00 roadside drug test kits that are known to give false positives. Now, this landmark study by the Quattrone Center demonstrates the scope of the harm done by these inaccurate test kits, including the disproportionate impact to African Americans," Des Walsh, founder of the Roadside Drug Test Innocence Alliance, said in a press release. "Based on this study, we look forward to working with law enforcement and other interested parties to implement policies and adopt better testing techniques to substantially reduce the tragic number of innocent people arrested and convicted because of these false tests."