Police say people who smoke weed have ‘green tongues.’ There’s no scientific evidence.
Defense attorneys and a Pennsylvania drug-recognition expert offer different opinions on green tongues being used as evidence in DUI cases. York Daily Record
Police officers across the United States have used the observation as one of several signs to justify probable cause and make arrests in criminal cases.
In the early morning hours of May 2, 2018, Amanda Guimond was driving through York County, Pennsylvania, 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 immediately 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.
Later, the police officer had a request for Guimond: Stick out your tongue. That’s when he said he noticed that there was a “green film” on it.
Guimond was handcuffed and placed under arrest on DUI charges after failing standardized field sobriety tests. She said she hadn’t smoked in about four hours. More than one year later, though, 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.”
A green tongue is seen in this photo illustration. Police officers have alleged for decades in some DUI cases that people who’ve recently smoked marijuana had green tongues. But there’s no scientific evidence that police can point to that shows marijuana causes someone’s tongue to turn green. (Photo: Paul Kuehnel, York Daily Record)
Police officers across the United States are alleging in some DUI cases that people who’ve recently smoked marijuana have green tongues. Law enforcement is even told to look for a “possible green coating” in one specialized training program that’s taught all over the world.
But police can point to no scientific studies that show marijuana causes someone’s tongue to turn green. Yet, for decades, they’ve used the observation as one of several signs to justify probable cause and make arrests in criminal cases.
“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.”
‘As sound as the science behind the earth being flat or that lying makes your nose grow’
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.”
The research led to a national look at the phenomenon.
Though green tongues are mentioned in several affidavits of probable cause, not everyone is convinced that the observation actually means anything.
Critics, including Scott Harper, a defense attorney in West York, describe it as “kind of junk science.”
Harper recently 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 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,” said Erik Altieri, executive director of NORML, 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.” (Photo: Paul Kuehnel, York Daily Record)
They’re not the only ones who’ve expressed doubts. So have courts in two other states.
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 recently used marijuana, Judge Elaine M. 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 A. Thorne Jr. wrote that the circumstances in the case and the trooper’s training and experience weren’t enough to support probable cause.
At one point, 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.”
Thorne said the court was “troubled” by the trooper’s reliance on a green tongue being “dispositive proof of marijuana use.”
‘It just doesn’t seem to go away’
Nick Morrow believes 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 traces the green tongue back to a handbook called “Identifying the Marihuana User,” which was published in 1986.
Dr. Forest Tennant Jr., 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.
Dr. Forest Tennant Jr., a physician in California who wrote a guide called “Identifying the Marihuana User” in 1986, included this picture in the handbook. (Photo: Submitted)
Today, Morrow works as a court-qualified expert witness and testifies for the defense.
Morrow said he doesn’t doubt that police officers are being trained to look for a green tongue by those they’ve trusted to provide them with the best information. 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 only seen one credible instance in his career — and it was on St. Patrick’s Day.
Said Morrow: “The guy was drinking green beer and smoking weed.”
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. (Photo: Paul Kuehnel, York Daily Record)
Where’s the evidence?
So where’s the evidence?
Law enforcement and traffic safety advocates all point to the same two peer-reviewed articles. But neither of them conclude 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 being taught in the Drug Evaluation and Classification Program.
The Drug Evaluation and Classification Program is an intensive training that educates police officers 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.”
But researchers looked at any mention of a coating on the tongue — not specifically a green one. And 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, who’s 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 were seeing in the field to see if 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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More than one indicator of drug impairment should be considered, experts say
Despite being unable to produce any definitive scientific studies, police officers are still being taught to look for a “possible green coating on tongue” in the training to become certified drug-recognition experts.
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.
Yet, 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.” But the 2018 version references two peer-reviewed articles — including one from 1998. (Photo: Dylan Segelbaum, York Daily Record)
A green tongue is “such a common phenomenon” that law enforcement included the observation in the training, said Kyle Clark, national project manager of the Drug Evaluation and Classification Program for the International Association of Chiefs of Police.
Clark 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.”
Andrascik disputed that the science is questionable. He said the green color is not outwardly observable most of the time because it’s on the back of the tongue.
A green tongue, he said, is simply one sign that might be there. He likened it to someone who uses methamphetamine having missing teeth.
“It’s such a minor detail to make a major issue out of something that’s really, really minor,” he said. “It’s not something that we’re basing any kind of opinion or actions on.”
Dave Andrascik, Pennsylvania’s Drug Evaluation and Classification Program state coordinator, said in an interview that drug-recognition experts are using the totality of the circumstances to render an opinion. He described the green tongue as a “such a minor detail.” (Photo: Paul Kuehnel, York Daily Record)
The use of green tongues as evidence reveals a larger 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 pupils; and a lack of coordination. And most of those cases have ended with convictions or acceptance into a diversionary program for first-time offenders.
But defense attorneys who are critical of green tongues being used as evidence in DUI cases say it speaks to a larger concern in the criminal justice system.
“It has the weight of scientific evidence,” said Matt Brown, a defense attorney in Arizona. “And it’s being used to deprive someone of their liberty.”
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.
But 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.
“This is just a pretty easy one to pick on because it just seems so facially ridiculous. Yet it has been accepted, unquestioningly, for years,” he added. “And what does that say about our ability, through the legal system, to seriously evaluate the quality of scientific evidence?”
Police officers, he said, are doing the best with the tools and training that they’ve been provided.
Gothie said he doesn’t fault them for implementing the “green tongue approach.” Instead, he said, he blames the people who are training them that it’s a sign of impairment.
Joe Gothie, a defense attorney in York, said there’s often overwhelming evidence in DUI cases — so a reference to a green tongue won’t make a different. But he expressed concerns about the willingness of the courts and law enforcement to accept unsupported scientific claims. “This is just a pretty easy one to pick on because it just seems so facially ridiculous. Yet it has been accepted, unquestioningly, for years,” he said. “And what does that say about our ability, through the legal system, to seriously evaluate the quality of scientific evidence?” (Photo: Cameron Clark, York Daily Record)
Steve Graham, a defense attorney in Washington who wrote a blog post about the green tongue phenomenon, said it’s been “repudiated by any court that actually takes the time to study the scientific literature.”
Graham wrote in the post that he once had a case in which police alleged that his client had “a green coating on his tongue.” But there was no marijuana found in his bloodstream. It was methadone.
Judges, he said, serve as gatekeepers to prevent scientifically unreliable ideas from being introduced as evidence. That’s why polygraph examinations are not admissible.
“If courts are allowing this sort of evidence, and the local police academies are not insisting on scientifically-reliable criteria, then drivers are going to be hassled and inconvenienced and falsely arrested and detained and embarrassed on the side of the road,” Graham said.
That’s what happened to one of Dan Gerl’s clients in 2017.
Gerl is managing partner at Puget Law Group, a DUI criminal defense firm in Washington. He represented a man who worked at a dispensary.
Police said the man had a “green, film-like substance and raised taste buds” on his tongue. He told law enforcement that he’d handled marijuana earlier and just ate a salad before being pulled over.
He was arrested on DUI charges.
The lab results were negative for marijuana — or any substances. Prosecutors later dropped the charges.
Guimond, the woman arrested on DUI charges in York County, was eventually accepted into a diversionary program for first-time offenders that will allow her to avoid a criminal conviction.
Prosecutors said her blood tested positive for marijuana.
Meanwhile, Guimond said she’d smoked hours before driving because she had a major headache. She had just finished working a 17-hour shift. And she said she was cold and anxious during the field sobriety tests.
But the reference to a green tongue, she said, is one of the main factors that bothered her about the arrest. That’s particularly because she said she’d just chugged a Monster Energy drink and eaten a Reese’s Peanut Butter Cup.
“I really hope this actually does something,” Guimond said. “Because green tongue identification for marijuana is bullshit.”
Contact Dylan Segelbaum at 717-771-2102.
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