Want the best of VICE News straight to your inbox? Sign up here.

Police across the country have used the same breed of shoddy $2 test to arrest people for cocaine that was really bird poop, meth that was actually crumbs from a glazed donut, and oxycodone that turned out to be vitamins.

In all of those cases, the possession or drug trafficking charges were eventually dropped after police sent the “drug” samples to a state lab that returned more-conclusive results. The original tests, known as presumptive field tests, have a history of being almost laughably wrong — if they weren’t putting people behind bars, even temporarily. And the follow-up lab tests that eventually clear people’s names can take weeks, if not months.

In the meantime, innocent people may be spooked into taking a plea deal instead of risking a longer sentence at trial. And if they can’t afford their bail, they’ll languish in jail as they decide whether to take a guilty plea or wait on better test results.

Cody Gregg, a homeless man in Oklahoma City, took the guilty plea in early October, supposedly because he wanted to get out of the city’s problem-plagued jail. Police charged him with possession after a field test incorrectly identified powdered milk inside a clear baggie as cocaine. He was sentenced to 15 years in prison and had been in jail for nearly two months before drug-lab results cleared him.

“You cannot indict somebody — put somebody in jail — over something you know has a very high rate of false positives,” Omar Bagasra, a biology professor at Claflin University and director of the South Carolina Center for Biotechnology. “It’s ignorance.”

Bagasra once participated in a study for the Marijuana Policy Project that found a common brand of police field tests incorrectly identified patchouli, spearmint, and eucalyptus as weed. His team even warned about “the serious possibility of tens of thousands of wrongful drug convictions.”

In an attempt to showcase just how faulty the tests were, the research team went before the National Press Club and repeatedly produced false positives for mundane things like chocolate bars.

‘A large group of false positives’

The most common presumptive field tests only cost a few dollars and are supposedly simple to use. That’s why they’re widely favored by police across the country and lead to thousands of arrests each year, according to a 2016 ProPublica investigation. The tests, however, have their downsides: They’re often not admissible in court, which is why police have to order follow-up testing from a lab.

To complete the field test, all an officer usually has to do is drop a sample of the suspect substance into a little pouch, break a capsule containing compounds that cause a chemical reaction, and wait a few moments. The pouch turns a specific color to alert the officer that drugs may be present.

The problem, according to Bagasra, is that the catalyzers, known as reagents, can positively react to a wide variety of chemicals but can’t distinguish to an officer what they might be reacting to. Plus, the colors the tests produce can be subjective, especially in bad lighting. (About 1 in 12 men are colorblind, and 88% of cops are men.)

"You cannot indict somebody — put somebody in jail — over something you know has a very high rate of false positives."

For example, the formula often used by local police to test for cocaine, cobalt thiocyanate, will likely turn a bright shade of blue when interacting with things like Benadryl or pain relievers, according to an online manual for Ohio’s state crime lab. Under the test’s description, the lab writes that there “is a large group of false positives.”

Plus, instead of being used in a sterile lab, the tests are often quickly used on the side of the road, in a cop car, or at the local jail, where they can be misinterpreted under bad lighting. The tests also often rely on cops — not well-trained scientists — to administer them.

The DOJ's Warning

In 2000, the Justice Department issued guidelines requesting the tests’ manufacturers include warning labels telling cops that the tests could produce false positives and therefore require appropriate training. But ProPublica’s investigation found those guidelines were largely ignored. Newer, more accurate tests are available, but police departments don’t typically buy them because they can cost tens of thousands of dollars.

“If officers are not trained to get the message that a positive drug test is more equivocal than the label would make you think, you’ll have police officers thinking, ‘Positive means it’s definitely drugs,’” said Carl Takei, a senior staff attorney at the ACLU’s Trone Center for Justice and Equality. Instead, a positive result means that the presence of drugs can’t be ruled out but should be weighed with plenty of other evidence before officers proceed.

Oklahoma City Police told VICE News that the officers did weigh other evidence in Gregg’s August arrest for possessing the powdered milk that tested positive for cocaine.

For example, Gregg had a prior history of drug convictions and ran from police when they attempted to stop him for a missing taillight on his bicycle. Once they retrieved the backpack he was carrying, they found the clear bag of a “white powdery substance” and a scale, too. All of those things factored into his arrest — not just the presumptive drug test.

“Field testing of possible drugs by officers is a presumptive test only and is simply one part of the totality of the circumstances that can lead an officer to believe that enough probable cause exists to legally effect an arrest,” Capt. Larry Withrow, a spokesperson for the Oklahoma City Police Department, told VICE News in an email.

Nonetheless, Withrow said: “We are reviewing our presumptive test procedures to determine if improvements can be made in this area.” He added that the department hasn’t had any problems with field tests before.

In Tulsa County, Oklahoma, about 100 miles away from where Gregg was arrested, public defender Natalie Leone said she handles a drug case with false positives from field tests about once a month.

This past May, Tulsa police found one of her clients, Carl Fisher, with a glass container of liquid that tested positive for meth in the field. Fisher, who’s homeless, was asleep in a car in a residential parking lot when officers approached him with guns drawn because they considered the car stolen. They tased him multiple times and dragged him out of the car, body-camera footage shows.

Fisher was arrested on drug charges, resisting arrest, and assault on a police officer. He was behind bars for nearly two months on what was initially a $160,000 bail before state lab results cleared him. He then remained in jail until October, when he agreed to plead no contest to the charge of resisting arrest.

“Reform to the bond system would really help, so that you’re not waiting in custody for lab results, at least,” Leone said.