YORK, Pa. – In the early morning hours of May 2, 2018, Amanda Guimond was driving through York County when the red and blue flashing lights came on. She was going more than 15 mph over the speed limit.

The Northern York County regional police officer smelled marijuana coming from inside her vehicle. Guimond, he wrote in an affidavit of probable cause, had glassy, bloodshot eyes, lethargic speech and a dazed and confused appearance.

The police officer requested that Guimond stick out her tongue and noticed there was a "green film" on it.

Guimond was arrested on DUI charges after failing standardized field sobriety tests. She said she hadn't smoked in about four hours. More than one year later, she said she's still bothered about the allegations concerning her tongue.

"Not once has my tongue ever changed to green,” said Guimond, 20, a cook and manager who's a medical marijuana patient and lives in Frederick, Maryland. “I was extremely shocked. I was very angry.”

Police officers have alleged in some DUI cases that people who recently smoked marijuana had green tongues. There’s no scientific evidence that police cited that shows marijuana causes someone’s tongue to turn green.

Police officers across the USA alleged in some DUI cases that people who recently smoked marijuana had green tongues. Law enforcement is told to look for a "possible green coating" in one specialized training program that's taught all over the world.

Police point to no scientific studies that show marijuana causes someone's tongue to turn green.

“If someone is going to be convicted, it should be based on facts proven beyond a reasonable doubt,” said Bradley Myerson, a defense attorney in Vermont. “Green tongue has nothing to do with marijuana ingestion, let alone impairment.”

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‘As sound as the science behind the earth being flat or that lying makes your nose grow’

The York Daily Record/Sunday News analyzed more than 1,300 DUI cases that reached the York County Court of Common Pleas in 2018 and found at least 28 that mentioned phrases such as "green coating," "green film" and "green tint.”

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The research led to a national look at the phenomenon.

Critics, including Scott Harper, a defense attorney in West York, describe it as “kind of junk science.”

Harper argued in a DUI case in York County that there’s “no evidence that a ‘green tongue’ is indicative of any specific degree of marijuana impairment (assuming it actually is evidence of anything at all).”

“I don’t even think it’s real,” Harper said. “They can take pictures of these things. I’m still waiting to see a green tongue someday.”

The National Organization for the Reform of Marijuana Laws was more blunt.

“The science behind marijuana consumption turning your tongue green is about as sound as the science behind the earth being flat or that lying makes your nose grow,” Erik Altieri, executive director of NORML, said in an email.

Scott Harper, a defense attorney in West York, described the green tongue phenomenon as "kind of junk science." "I don’t even think it’s real," he said. "I’m still waiting to see a green tongue someday.”

In 2000, the Washington Court of Appeals upheld a ruling to throw out a case that arose from a traffic stop in which a state trooper partly used the observation of a green tongue to justify a request to search the vehicle.

Even if a green tongue indicates that someone used marijuana, Judge Elaine Houghton wrote in the opinion, the absence of other observations and the many innocuous ways that could happen showed that there was a lack of reasonable suspicion.

“Although we assume the officer's assertion to be true for purposes of this opinion, we are nevertheless skeptical as to its accuracy,” Houghton said. “We find no case stating that recent marijuana usage leads to a green tongue.”

The Utah Court of Appeals ruled in 2004 that a state trooper arrested a man on a hunch when he used observations including a green tongue.

In the opinion, Judge William Thorne wrote that the circumstances in the case and the trooper’s training and experience weren’t enough to support probable cause.

Thorne specifically addressed the green tongue. He noted that the state had “presented nothing, no scientific studies and no case law or other authority, to support the reliability of the trooper's concern.”

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It 'just doesn’t seem to go away’

Nick Morrow said he knows the origin of the green tongue phenomenon.

From 1984 to 1995, Morrow worked in the Los Angeles County Sheriff’s Department, where he was a certified drug-recognition expert and instructor. He was a self-described "complete drug nerd" who sought to learn as much information as possible about the subject.

Morrow traced the green tongue back to a handbook called “Identifying the Marihuana User," which was published in 1986.

Forest Tennant, the physician who wrote the guide, included a picture of a person with a green tongue in the handbook. He dedicated it to the California Highway Patrol.

Forest Tennant, a physician in California, wrote a guide called "Identifying the Marihuana User" in 1986, which included this picture.

Morrow works as a court-qualified expert witness and testifies for the defense.

Morrow said he doesn’t doubt that police officers are trained to look for a green tongue. It’s been in the law enforcement culture for decades. The phenomenon, he said, “just doesn’t seem to go away.”

He said he’s seen only one credible instance in his career – and it was on St. Patrick’s Day.

“The guy was drinking green beer and smoking weed,” he said.

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The York (Pa.) Daily Record/Sunday News analyzed more than 1,300 DUI cases that reached the York County Court of Common Pleas in 2018 and found at least 28 that mentioned phrases such as "green coating," "green film" and "green tint.” Some of the affidavits of probable cause that reference the observation are pictured in this photo illustration.

Where’s the evidence?

Law enforcement and traffic safety advocates point to the same two peer-reviewed articles, neither of which concludes that marijuana causes someone's tongue to turn green.

The first article was published in the Journal of the American Optometric Association in 1998. Two of the five authors worked in law enforcement: Oregon State Police Lt. Charles Hayes and Senior Trooper Richard Evans.

The paper states, without a citation, that people who've recently smoked marijuana "might have a greenish coating" on the back of their tongues.

In an interview, Karl Citek, an optometry professor at Pacific University in Forest Grove, Oregon, who's one of the authors, said they reported on what police officers were taught in the Drug Evaluation and Classification Program.

The Drug Evaluation and Classification Program is an intensive training course that educates police officers on how to recognize if people are under the influence of drugs and determine what substance is causing impairment.

If optometrists have knowledge of the program, the article concludes, that could allow them to serve as consultants to the police and testify as expert witnesses.

Citek said the authors weren't conducting original research to determine whether marijuana causes someone's tongue to turn green – though he's personally witnessed the phenomenon.

“It was intended to be more educational than anything else,” Citek said. “And, hence, it’s a review paper.”

The second article was published in the Journal of Forensic Sciences in 2017.

Researchers tested blood samples from people who were suspected of driving under the influence.

Police officers documented that 185 drivers had a "coating on the tongue." When the toxicology came back, 96.2% of them had THC in their system. That’s the ingredient in marijuana that causes a high.

“The objective signs of red eyes, droopy eyelids, affected speech, coating on the tongue, and the odor of marijuana are very reliable in indicating the presence of THC in the blood,” the study reads. “This is not surprising as they represent the most common symptoms of consuming marijuana."

Researchers looked at any mention of a coating on the tongue – not specifically a green one. The paper contains the following note on the first page, “Authors all work for The Orange County Crime Laboratory testifying on driving under the influence cases, specifically in regard to marijuana, which represents a possible conflict of interest.”

Ariana Adeva, supervisor of toxicology and one of the authors, said researchers didn't draw any conclusions about whether marijuana causes a coating on the tongue.

Instead, she said, they looked at trends that police officers saw in the field to see whether they corresponded to THC in the blood.

"I think it is a common finding," Adeva said of a coating on the tongue. "We did see a good number of cases including it."

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The 2018 Drug Recognition Expert Course instructor guide states that “a greenish coating on the tongue has been documented in two peer‐reviewed articles.” Those two peer-reviewed articles? The same ones from 1998 and 2017.

As recently as 2015, the instructor guide contained the following note: “Point out that there are no known studies that confirm Marijuana causing a green coating on the tongue.”

The 2015 Drug Recognition Expert Course instructor guide tells teachers to "point out that there are no known studies that confirm Marijuana causing a green coating on the tongue."

Kyle Clark, national project manager of the Drug Evaluation and Classification Program for the International Association of Chiefs of Police, said he doesn't know precisely what causes the green tongue. He said it's been incorporated into the training manuals since at least 1992.

“We’re just saying we see it,” Clark said. “We have it in our manuals because it’s a frequently encountered occurrence.”

Dave Andrascik, Pennsylvania’s Drug Evaluation and Classification Program state coordinator, noted that the 12-step drug influence evaluation takes 35 to 45 minutes to complete.

Drug recognition experts, he said, look at the totality of the circumstances to render an opinion. He said there’s more than 400 different indicators of impairment for the seven categories of drugs. It doesn’t make sense, he said, to look at one factor in a vacuum.

“Just because someone has a green tongue doesn’t mean they smoked marijuana,” said Andrascik, who’s with the Pennsylvania DUI Association, a professional organization that works to address the problem of impaired driving. “But the fact that someone has a green tongue and their blood pressure’s increased and their heart rate’s up and their pupils are dilated and they have red eyes – it’s a totality of everything."

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Dave Andrascik, Pennsylvania’s Drug Evaluation and Classification Program state coordinator, says drug recognition experts use the totality of circumstances to render an opinion. He described the green tongue as "such a minor detail."

Concern in the criminal justice system

Police didn’t solely rely on the observation of a green tongue to make an arrest, according to the York Daily Record analysis. They noted other signs that might indicate impairment including glassy, bloodshot eyes, dilated pupil; and a lack of coordination. Most of those cases ended with convictions or acceptance into a diversionary program for first-time offenders.

The evidence in these cases is often overwhelming, so the mention of a green tongue isn't going to make a difference, said Joe Gothie, a defense attorney in York.

Gothie said he’s concerned about the willingness of courts and law enforcement to accept an unsupported scientific claim.

“We have a duty to question all this sort of forensic or scientific evidence that comes out,” Gothie said.

Joe Gothie, a defense attorney in York, said there's often overwhelming evidence in DUI cases, so the mention of a green tongue isn't going to make a difference. But he expressed concerns about the willingness of courts and law enforcement to accept an unsupported scientific claim.

Follow Dylan Segelbaum on Twitter: @Dylan_Segelbaum

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This article originally appeared on York Daily Record: Police say 'green tongues' a sign of smoking weed, but no evidence