Series: Busted Examining Chemical Field Tests

The Clark County District Attorney’s Office in Nevada established a conviction review unit in October. In what appears to be one of its first efforts, the unit has been seeking information about problematic convictions resulting from one of the office’s routine practices: accepting guilty pleas in drug cases that rely largely on the results of field tests done by police that can be unreliable.

Daniel Silverstein, head of the newly formed unit, in November asked a statewide organization of defense lawyers for any information they had on cases that might have involved inaccurate field tests, and thus resulted in potentially wrongful convictions. Police place suspicious material into a pouch of chemicals that are supposed to change color to indicate the possible presence of illegal drugs. The $2 tests are used by police departments nationwide, and over nearly 30 years in Clark County they have helped produce tens of thousands of drug convictions for the possession or sale of cocaine, methamphetamine and marijuana. In the vast majority of those cases, the field test results are never confirmed in a formal crime lab.

Earlier this fall, ProPublica reported that the district attorney’s office had long known that the tests were prone to error, and that the Las Vegas Metropolitan Police Department’s crime lab had produced a study in 2014 detailing the vulnerabilities of the tests. The district attorney’s office nonetheless continued to gain convictions in cases involving field tests, and collaborating with the Las Vegas police crime lab, even expanded their use to obtain convictions in cases of suspected heroin. The crime lab’s study was not shared with the judges who approve plea deals.

In October, the district attorney’s office declined to answer questions about its practices involving field tests, and officials would not be interviewed regarding the recent actions taken by the conviction review unit.

Silverstein, the conviction review director, responded by email: “At this time, I have no comment on this issue.”

Laurie Diefenbach, a veteran Las Vegas defense attorney, said the Nevada Attorneys for Criminal Justice has distributed Silverstein’s request to its members. The organization represents the state’s defense bar.

ProPublica’s reporting, done in partnership with the Las Vegas Review-Journal, prompted defense attorneys in Las Vegas to organize a committee aimed at exploring ways to formally challenge the routine use of the field tests in drug cases. The attorneys have said all parties in the local criminal justice system — judges, prosecutors, and they themselves — had a moral obligation to reform the reliance on unconfirmed field test results to underpin convictions.

Busted 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.

In 2014, prosecutors in Harris County, Texas, discovered that hundreds of people had pleaded guilty to drug crimes based on what proved to be erroneous field tests. As a result, the district attorney’s office revised its policies so that no guilty pleas would be accepted in drug cases unless there had been confirmation of field-test results by the local crime lab.

Defense lawyers in Las Vegas reacted to the request for information on potentially wrongful convictions with disdain. Some attorneys questioned the vigor of the conviction unit’s efforts, saying it was virtually impossible for defense attorneys to know whether the field tests that had helped convict their clients were faulty.

Prosecutors routinely delay crime lab analysis to check results of field tests until the eve of trial, court records show. When defendants plead guilty at preliminary hearings, the alleged drugs rarely even reach the lab. In Clark County last year, according to court data, just eight of 4,633 drug convictions went to trial.

The police department destroys samples after convictions are entered and does not track how many of its field test results are confirmed. Drug arrest and lab testing data show the number could be as low as 10 percent.

Howard Brooks, the Clark County Public Defender’s appellate director, called the district attorney request to defense attorneys “an absurd challenge.” Brooks argued it is the duty of prosecutors to verify the integrity of their convictions — both those that have already been won and those being brokered today in Clark County courts.

“It’s about whether or not your convictions mean anything,” Brooks said.

Diefenbach said members of the Nevada Attorneys for Criminal Justice are preparing to challenge the test kits’ reliability and officers’ training during preliminary hearings.

Given the district attorney’s office’s refusal to discuss its efforts, it is unknown whether Silverstein’s unit has identified any drug convictions to scrutinize.

Phil Kohn, the Clark County public defender, said it was clearly time for all criminal drug evidence to be analyzed by forensic scientists to protect against wrongful convictions.

“How do you prevent the next one,” Kohn said, “when they won’t test all of them?”