Opinion writer

A new report from ProPublica and the Las Vegas Review-Journal finds that since the early 1990s, the Las Vegas Metropolitan Police Department has been using cheap drug field-test kits to determine whether found substances are illegal. While far too many police agencies have used the kits to determine probable cause for a search, in most cases the substances are later more thoroughly tested at a crime lab. In Las Vegas, the test results were apparently also used as evidence to help prosecutors win convictions.

It gets worse.

All along, though, police and prosecutors knew the tests were vulnerable to error, and by 2010, the police department’s crime lab wanted to abandon its kits for methamphetamine and cocaine. In a 2014 report that Las Vegas police submitted to the U.S. Department of Justice under the terms of a federal grant, the lab detailed how the kits produced false positives. Legal substances sometimes create the same colors as illegal drugs. Officers conducting the tests, lab officials acknowledged, misinterpreted results. New technology was available — and clearly needed to protect against wrongful convictions.

Yet to this day, the kits remain in everyday use in Las Vegas. In 2015, the police department made some 5,000 arrests for drug offenses, and the local courts churned out 4,600 drug convictions, nearly three-quarters of them relying on field test results, according to an analysis of police and court data. Indeed, the department has expanded the use of the kits, adding heroin to the list of illegal drugs the tests can be used to detect.

There’s no way to quantify exactly how many times the field tests were wrong or how many innocent people pleaded guilty based on the inaccurate results, or to assess the damage to their lives.

This should be a massive scandal. If police and prosecutors are knowingly using drug test kits known to have a high false positive rate, and then using the results of those tests to put people in prison, they are knowingly violating the constitutional rights of those people. Not only do a lot of people need to be fired, but there also ought to be a criminal investigation.

The department maintains it has never established an error rate. The department destroys samples after pleas are entered and does not track how many of its field test results are re-checked. Drug arrest and lab testing data show the number could be as low as 10 percent.

But if two-thirds of drug convictions are based on the test results, and there were 4,600 such convictions, then a 10 percent error rate for the test kits would mean that more than 300 people were wrongly convicted last year alone. As the report points out, in Houston 300 people were recently found to have falsely pleaded guilty to a drug charge after a faulty result from a drug test kit. We only know this now because in Houston the policy is to save the results of such tests even after a guilty plea. In Las Vegas, the kits are destroyed.

To make matters worse, the report found that prosecutors often let defendants arrested based on kit results to linger in jail before sending substances to the crime lab for more thorough analysis. For a low-income person who has kids or is missing work, it can be awfully tempting to accept a plea and take, say, probation, rather than wait weeks for test results. The report also found that prosecutors and police often vouched for the tests’ reliability. Moreover, it takes just 4 grams of cocaine, meth or heroin to bring a trafficking charge in Nevada. That means that faulty field test results on, say, talcum powder or cornstarch will (a) result in much higher bail and (b) bring the threat of much more serious prison time, putting more pressure on even an innocent suspect to plead guilty to a lesser charge of possession.

As we’ve discussed before here at The Watch, these tests don’t just provide evidence for arrests and criminal charges. They also provide probable cause for drug search warrants, including warrants executed with violent, highly volatile tactics like “dynamic entry,” flash grenades and SWAT teams. Which means these tests are also subjecting innocent people to unimaginable violence and terror.

So why would police agencies continue to use faulty tests? Well, for one, the tests are cheap. The less charitable explanation is that police tend to trust their hunches. Even if the powder or plant material they find under the floor mat isn’t illegal, a test showing that it is gives them cause for a more thorough search. Cheap tests that err on the side of confirming police suspicions mean more searches, more arrests and more convictions. Conducting more searches means more opportunities for asset forfeiture. Making more arrests looks good for cops. And getting more convictions looks good for prosecutors. Everybody wins. Except, of course, for those 300 or so innocent people convicted of a drug crime — or the innocent family members who wake up to SWAT officers pointing guns at their heads.