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Texas Panel on Wrongful Convictions Calls for Ending Use of Unverified Drug Field Tests

A commission established by lawmakers to help end the conviction of the innocent says field tests are too unreliable to be trusted without lab confirmation.

Drug field tests are too unreliable to trust in criminal cases, according to a Texas courts panel, which has called on crime laboratories across the state to confirm drug evidence actually contains illegal drugs for every prosecution.

State lawmakers created the Timothy Cole Exoneration Review Commission in 2015 to research wrongful convictions in Texas and suggest ways to prevent future injustices. The commission named field tests as a significant concern in its final report, released last month, due to their “questionable reliability.”

In Houston over the past decade, the crime lab found that the alleged drugs in more than 300 convictions were not drugs at all. Police had used inexpensive test kits to identify the substances as cocaine, methamphetamine, heroin, MDMA, or marijuana, and prosecutors had used those allegedly positive tests to gain guilty pleas.

The commission initially excluded drug cases from its review, but reversed its decision following a ProPublica story, published with The New York Times Magazine, that detailed the central role field tests played in Houston’s wrongful convictions.

Texas criminal courts process roughly 10,000 drug possession convictions a year. Having crime labs check the evidence in each would likely prove expensive, the commission acknowledged. “Despite potential additional costs in implementing this practice, requiring laboratory testing of all drug field tests will reduce the risk of wrongfully arresting and convicting an individual of being in possession of a controlled substance,” the report states.

The 11-member exoneration commission was made up of state lawmakers, a criminal appellate judge, representatives from the state’s defense bar, prosecutors, police, judiciary, and the forensic sciences.

In addition to restricting drug field tests, the commission called for audio recording of police interrogations in all felony cases, tighter rules on testimony from jailhouse informants, and mandatory training for officers in eyewitness identification. It formally submitted the report to the state legislature, where lawmakers can consider turning its proposals into law.

ProPublica spent 2016 examining the widespread use of field tests by police departments and prosecutors across the country. No government agency regulates their use. The patrol officers who perform the tests to make arrests on the street often have little or no training in the use of the tool. Most of the nation’s crime laboratories do not check officers’ field tests when defendants plead guilty.


Tens of thousands of people every year are sent to jail based on the results of a $2 roadside drug test. Widespread evidence shows these tests routinely produce false positives. Why are police departments and prosecutors still using them? Read the story.

Police and prosecutors began relying upon the tests’ results decades ago, and they were seen as a cheap but efficient way of establishing probable cause for an arrest while not swamping already overworked crime labs. They were never designed to be used as evidence at trial, and indeed courts across the country have routinely barred them. But with the growing ubiquity of plea bargains, the tests have in many instances effectively served as evidence used against suspects to win convictions.

ProPublica’s reporting showed that in Las Vegas, the police department’s crime lab and local prosecutors were aware of the tests’ reliability problems, but failed to disclose the flaws to judges who ultimately approve the resulting guilty pleas. The tests in Las Vegas are not confirmed in a lab in a vast majority of the thousands of drug cases generated each year.

In the wake of ProPublica’s reporting, done in partnership with the Las Vegas Review Journal, the Nevada Attorneys for Criminal Justice, which represents the defense bar, formed a committee to devise legal strategies to challenge unconfirmed field test results.

In Portland, Oregon, ProPublica’s reporting prompted the district attorney for Multnomah County to mandate that all field tests be checked by a crime lab, even in cases where a defendant has already pleaded guilty. The office also vacated the convictions of five men who had pleaded guilty based on erroneous field tests.

Scrutiny, and skepticism, of the test kits might soon increase further.

The Texas Forensic Science Commission is considering a formal investigation of field tests and how police officers perform them, said Lynn Garcia, the agency’s general counsel.

The forensic science commission is a regulatory agency that oversees the state’s crime laboratories and analysts. It has a broad mandate, which includes scrutinizing whole categories of forensic science to determine if the evidence law enforcement uses is sound. Field tests are on the agenda for the agency’s next public meeting in February.

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