Bird poop scraped off a man’s car appeared on a drug test as cocaine. A toddler’s ashes registered as methamphetamine or ecstasy.

And a great-grandmother’s medicine tested positive for cocaine – spawning a 15-month legal nightmare, forcing her to refinance her home, and spurring a new state law that could set a precedent across the country.

Colorado just enacted the nation’s first law banning arrests based solely on the results of colorimetric drug tests – a field test widely used by law enforcement across the country.

The tests are popular because they’re cheap, portable and can screen for drugs in mere minutes. It’s just not feasible to send all suspected drug samples to state laboratories, which would be far more expensive and could take days or weeks to return results.

But these inexpensive tests also lead to false positives at alarming rates, researchers from the University of Pennsylvania found.

While the actual error rate nationwide is unknown, previous studies by manufacturers have put it around 4%. But the UPenn researchers believe the actual rate is much higher, from 15% to 38%. And a study by the New York City Department of Investigation showed test error rates from 79% to 91% in some correctional settings.

From lost jobs to months in jail, innocent people “are at risk of having their lives derailed by these inaccurate tests,” said Des Walsh, founder of the Roadside Drug Test Innocence Alliance.

Colorimetric tests are pouches containing chemicals that change color when certain substances or compounds are detected.

They typically cost between $2 and $10 and are used by law enforcement agencies across the US, Walsh said.

By contrast, more reliable and portable electronic devices can cost from $24,000 to $80,000 – “hence the continued reliance on a $2 roadside drug test,” Walsh said.

While the design can vary by manufacturer, the pouches contain “different chemicals that are intended to react with the compounds found in different narcotics,” Walsh said. “So there are tests for cocaine, for methamphetamines, for heroin, for fentanyl.”

But many everyday items have compounds that can also trigger a positive result. “For example, the chemical characteristic of amphetamine has similar characteristics to the chemical compound for sugar,” Walsh said. That’s why sugar and sugar substitutes can show up as controlled substances on colorimetric tests.

Even colorimetric test makers say their products only screen for the possibility of illegal drugs – and should not be considered tools for verification.

“NOTE: ALL TEST RESULTS MUST BE CONFIRMED BY AN APPROVED ANALYTICAL LABORATORY!” reads one warning for a pack of colorimetric tests.

“The results of this test are merely presumptive,” it says. “Reactions may occur with, and such compounds can be found in, both legal and illegal products.”

Still, horror stories have emerged when ordinary people are arrested and jailed over colorimetric test results.

Bird droppings and human remains test positive for drugs

Former Georgia Southern University quarterback Shai Werts was suspended from the team after he was pulled over for speeding in South Carolina and charged with cocaine possession, CNN affiliate WXIA reported.

During the traffic stop, a deputy noticed white residue on the hood of Werts’ car and ran it through a colorimetric test. The sample tested positive for cocaine.

Werts fought the case, and a lab test later confirmed the substance he said was bird poop was not cocaine. His suspension was lifted, and the deputy resigned months later.

Another traffic stop led to officers claiming a 2-year-old girl’s cremated remains were methamphetamine or ecstasy.

Illinois officers pulled over Dartavius Barnes and found a small urn in his vehicle. “I checked for cocaine, but it looks like it’s probably molly” – a slang for ecstasy, one officer said on bodycam video. When police showed Barnes the urn, he pleaded with them to give it back. “No, no, no, bro. That’s my daughter,” he said.

Poor lighting – especially at night – can make the results of colorimetric tests difficult to interpret, Walsh said.

In Florida, Kena’z Edwards was jailed because he couldn’t pay the $178,000 bond set after a bottle of lidocaine found in his car tested positive for cocaine, The Florida Times-Union reported. He spent more than three months behind bars because the local district attorney’s office only tested samples in a lab after a trial date is set.

But colorimetric drug tests aren’t limited to traffic stops. Studies show false-positive rates are especially high in prisons, which can lead to unfair punishments for inmates. Many samples taken from incoming mail have contaminants on the paper or in the ink, Walsh said. Commissary items such as soap, chocolate and coffee can also test positive.

Even children can be victims of false-positive tests. In Iowa, a 13-year-old girl was expelled from school last year “because the cookies she brought to school tested positive for THC on a field drug test,” Walsh said.

The cookies were tested because another student felt sick – though the cause of that illness was unclear. Regardless, the 13-year-old couldn’t go back to school for months. “It took her mom months to get a laboratory test that proved there was no THC or any illegal substance in the cookies at all,” Walsh said.

And in Colorado, a retiree’s nightmare became a catalyst for change.

A hospitalized great-grandmother was charged with cocaine possession

Holly Bennett was already in severe distress when a police officer entered her hospital room and accused her of stashing cocaine in her purse.

She suffered from “a bone infection from my cervical spine all the way down to my hips and pelvis,” the 65-year-old Coloradan said. Bennett underwent emergency surgery on her neck “because my arms were getting paralyzed.”

As she slowly woke up from surgery, Bennett was startled to see an officer in her room.

“He said, ‘I’m with the Lafayette Police Department, and I’m here to issue you a ticket for possession of cocaine,’” Bennett said.

When Bennett insisted she didn’t have cocaine, “He said, ‘Well, that’s what you had in your purse,’” she recalled.

It’s not clear who inspected Bennett’s purse and reported the contents to authorities. “Due to federal privacy laws that protect sensitive patient information, we are unable to respond to specific patient questions,” Intermountain Health said in an email to CNN.

“Circumstances can arise where conducting a personal belonging search is needed to maintain a safe and secure care environment for all patients, caregivers, and visitors,” the hospital network added.

Lafayette police Sgt. Jeremy Molander said he did not find records for Bennett’s October 2022 case. After a 2020 state law reduced penalties for certain drug offenses, he said officers in such cases typically issue a summons instead of making an arrest.

But Bennett said she shouldn’t have had to fight the legal system at all.

“What I had in my purse was a few Ritalin that were prescribed to me. It’s in my prescription records,” she said. “And they had broke down, just from movement, from me throwing my little bag around.”

Investigators could have checked her blood test at the hospital, which detected only her regular medication and not cocaine, she said.

The next 15 months were “pretty miserable” as the disabled senior fought her case and begged to have the sample tested in a lab. She refinanced her home to free up money as she struggled to find an affordable attorney.

“I kept going to court without a lawyer,” Bennett said. There, prosecutors pressured her to plead guilty in exchange for diversion – a six-month program that, if completed, would erase the drug charge from her record, she said. But diversion programs can cost innocent people time and money, through no fault of their own.

For those who get arrested due to colorimetric testing, “over 90% of people are taking a plea deal because they can’t afford to remain in jail and wait six months for laboratory tests,” Walsh said.

Bennett even offered to pay $500 for a lab test – even though she “really didn’t have it.”

“It would have been something that would hurt our ability to pay utilities,” she said.

At the time, the state lab was so busy that samples were only tested “if cases were set for trial,” Boulder County District Attorney Michael Dougherty said. “So that was part of the delay as well.”

After several months, Bennett found an attorney. Her trial date was set, and the substance from her purse was examined in a lab. In the end, she didn’t have to pay to retest the sample – “I guess because there was no cocaine in it.”

The district attorney’s office dismissed Bennett’s charge, Dougherty said, and records related to her case were expunged per Colorado law – including the original police report.

“They were wrong, and I was right,” Bennett said. But she worries about others who could be wrongfully charged, losing their jobs and languishing in jail for months while waiting for a trial date or for a lab test.

The district attorney agreed and said the system was flawed. So, his office teamed up with Bennett’s attorney, lawmakers, the Korey Wise Innocence Project and law enforcement officials to find a solution.

Dougherty said he had no idea how inaccurate colorimetric tests could be until Bennett’s case, which came a year before the UPenn study was released.

“With what we know now about the colorimetric field drug test, we’re going to be much more careful about whether the results that indicate it’s positive are accurate or not,” the district attorney said.

Most law enforcement agencies in Boulder County don’t use colorimetric tests, he said. But others in Colorado do. The top deputy in his office joined a state task force that helped craft legislation banning officers from arresting someone based solely on results from those presumptive field tests.

“Everyone, at every stage, seemed to blindly trust the results of this test,” said Bennett’s attorney Noah Stout, who also served on the state task force.

Stout said lawmakers were already considering possible new legislation before learning about Bennett’s case. But the great-grandmother’s ordeal “kicked it into special gear.”

“It’s sad that it takes an old lady in a walker who has no drugs in her system to demonstrate that this is wrong,” Stout said.

“And there are a lot of people who don’t check all those sympathetic boxes, who are more likely to face consequences and don’t have the means to retain private counsel and have the will to” fight the system, he said. “There’s a huge gap between the individuals who qualify for a public defender versus who actually can afford an attorney.”

Gov. Jared Polis signed the bill into law last week. The statute is the first in the nation to address colorimetric drug testing, the National Conference of State Legislatures told CNN.

Now, “Law enforcement needs confirmation beyond the colorimetric test,” Dougherty said. “For example, if the officer says, ‘What is this?’ and the person says, ‘It’s cocaine’ or ‘I’m addicted to meth and it’s meth,’ that could lead to a charge.”

Or “let’s say the person was driving 100 miles per hour and committing a crime and they also had some powder on them. There would be another criminal charge,” he said. “It can’t be a sole charge of a level-one drug misdemeanor with the sole evidence being the colorimetric test.”

Supporters of the new Colorado law hope other states will follow suit. But until then, innocent people with vitamins, powdered milk or cotton candy could be implicated by false positive tests.

The best tool for minimizing false positives in the field is to give officers more accurate, electronic testing devices, the Roadside Drug Test Innocence Alliance said.

They’re still not as reliable as lab tests, Walsh said. But electronic testing devices are more accurate than colorimetric tests “because you’re using laser technology or other technologies that will give you a specific chemical fingerprint – not simply looking for a generic aspect of a chemical compound that can be common to both narcotics and totally innocuous substances like soap or chocolate or prescription medication.”

Many urban police departments and some rural jurisdictions have started using them – including Lafayette police in Colorado.

The department has one electronic drug testing kit, which cost more than $24,000 when it was purchased, Molander said. Officers are “strongly encouraged” to use the more sophisticated test – not just because it’s more reliable, but because officers don’t need to open pouches to test substances, “potentially exposing themselves to dangerous drugs.”

But it’s too expensive to put an electronic testing device in every patrol car, and it’s not always practical to return to the police station to run a test. So, field officers might use colorimetric tests – which cost his department about $5 each, Molander said.

Colorimetric tests are still valuable “when used as a screening tool or as a basis for further investigation,” Walsh said.

But he said the costs of portable electronic devices would be well justified. Unlike colorimetric tests, which need to be replaced after every use, electronic devices can be used indefinitely, Walsh said.

More reliable tests would also save taxpayers money because fewer innocent people would clog the criminal justice system.

“It helps reduce jail overcrowding. It helps reduce the cost of unnecessary prosecutions,” Walsh said. “Everybody benefits from more effective testing.”