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Drug DUI | Drugged Driving | DRE | Arizona DUI


The Essential Guide

Drug DUI | Driving While Drugged | Arizona

If you are arrested for Driving While High, accused of a Marijuana DUI, or maybe a Prescription Medication DUI then you have come to the right place.

Here, you will find information about: 

  • Police Drug Recognition”Experts
  • The Scientific Foundations of DRE Evaluations
  • The scientific validity of what the DRE protocols claim



Drug Evaluations

The Big Problem

The Three Claims

12 Step Protocol


The Matrix




Supporting Studies


Statistical Flaws


Chemical Testing


Discovery Requested


Big Takeaways


We Are Dealing With a Placebo

Here is my thesis: the DRE protocols are a placebo. In Latin, placebo means: “I shall please.”  And that’s exactly what the protocols do.  They please, or satisfy the needs of a large group of people.  But it may not be the group you are thinking of…or the needs you may have imagined.

Watch how a placebo works

Take Astrology as an example.

Give two astrologers the same fact pattern.  Ask each of them the same question about the future.  If you make the question specific enough, then they will never give you the same answer (other than by random chance).


At the same time, there are some people who undoubtedly receive some real benefit from the story they are told by an astrologer. 

Its Story is Its Power

That is what a placebo does.  It takes something fake and makes it into something real.  It tells a convincing story to it’s recipients which resonates.   This story is a placebo’s real power.

DRE Protocols Are a Placebo

What I am arguing:

Law enforcement’s DRE protocols, used to make arrest decisions in drugged driving cases, are just a placebo.  They are something fake, that does something real.

Placebo For Who?

Placebo’s are used to help resolve a real problem causing a person to suffer in some way.

In the case of the DRE Protocols, unlike in the world of medicine, they are not a placebo for the subject of an evaluation.   Rather they are intended for the people the results of a DRE evaluation are presented.


This placebo is designed for judges, juries and the rest of the justice system.

What Are They Suffering From?

The exact malady is hard to diagnose.  However, after years of being on the factory floor of these issues, I have observed what can only be described as a complex recipe of bias

Perhaps people don’t want to believe – they live in a world where police can arrest innocent people…despite the fact they do.

Perhaps people don’t want to believe – they live in a world where police don’t have the ability to determine if a person is impaired by a drug …despite the fact they claim they do.

I can’t tell you the specific form of bias they suffer from…I can merely tell you…they do suffer.

The Effect of This Placebo:

Innocent People Are Being Convicted (Drugged Driving)

Drug Recognition Evaluations

For decades police have focused their DUI enforcement efforts on cases where alcohol caused impairment. At the same time, alcohol is merely one of the many drugs that can impair your ability to drive. More recently, police have placed a greater emphasis on DUI cases were impairment is alleged to have resulted from drugs such as marijuana and prescription medications.

Prescription Medication DUI
Drug metabolism

The shift, to an emphasis on drugged driving enforcement, presents a significant challenge for law enforcement. This arises from the fundamental fact that – drugs affect the body much differently, and much less predictably – than alcohol.

Accordingly, the police needed a new tool for drug DUI cases.

In the 1970s, the Los Angeles Police Department (LAPD) began developing a program to address DUI cases where the person had no alcohol in their system. In those cases, they wanted to identify if impairment may have resulted from drugs.

Police created a procedure that claimed it could recognize drug impairment. They called it the “Drug Influence Evaluation” (DIE).

LA Police Dective Badge

At the time the program was formally recognized there was no valid scientific evidence supporting the program’s validity. Currently, despite the government’s claims, this still appears to be the case.

The Big Problem

There are two fundamental problems at the core of police drug evaluations. These problem are illustrated by the difference between how alcohol and other drugs interact with the body.

The Cause of Impairment?

Some physical symptoms can be a good indication that a person is impaired. Some physical symptoms, in an of themselves, are impairment (i.e. a person limping who does not normally limp). However, determining the cause of any symptom(s) can be both complex and complicated.  Some causes are more difficult to identify then others.

Alcohol DUI

With Alcohol

To determine if alcohol is truly the cause of a person’s impairment, more than mere physical observations are required. You also need a scientifically valid chemical test. One capable of specifically showing whether the person was impaired by alcohol.

Universal Impairment Level

There is a universal level of impairment for alcohol. At .08, everyone is impaired for the task of driving. Thus, a properly conducted blood (or breath) test can at least raise a presumption that a person is impaired by alcohol. 

There is a universal level of impairment for alcohol. At .08, everyone is impaired to at least the slightest degree for the task of driving. Thus, a properly conducted blood (or breath) test can provide some level of reliable, but still rebuttable, evidence of impairment by alcohol.

Medical Marijuana Arizona

But With Drugs

No such universal level of impairment exists. Thus, there is no chemical test capable of revealing if impairment is caused by the exposure to a drug. Among other differences, unlike alcohol, the effects of a drug will significantly vary from person-to-person. Tolerance to drugs and medications also develop at different rates.

In sum, the DRE protocols are fundamentally flawed because:

1. It is generally accepted in the scientific community that the results of a chemical test are not capable of determining impairment was caused by a drug (other than alcohol in some cases).

2. Similarly, it is also generally accepted, that physical symptoms alone cannot determine that a drug caused the symptoms observed.

However, despite these flaws, the DRE protocols still claim to have the ability to identify drug impairment…and more.

The Three Claims

After a DRE officer conducts an evaluation, using a twelve-step protocol, they purport the ability to answer three questions:

1. Whether the suspect is under the influence (i.e. impaired) by a drug to operate a vehicle safely?

2. What category of drug is causing the impairment?

3. Whether the impairment is caused by a drug or medical issue?

Let’s see if these claims can be verified

Medical Rule Out

The third claim requires the ability to discern impairment caused by a medical condition – from – impairment caused by a drug.

This is an extremely difficult task that requires expertise in several different areas of medical specialization. 

More Likely

The DRE protocols require an officer to analyze whether the symptoms are more likely to be caused by a drug or medical condition.

How does an officer make such a determination? They do it without having the necessary knowledge and experience to make such a claim.

What is the evidence, resulting in a probability, favoring one cause versus another?

In every case where an officer has ruled out a medical cause in favor of a drug – the above question must be posed to the DRE officer.

DRE Only Equal PC

It is also essential that we look at the fine print of these claims.  That is, if these claims are true, then to what degree of certainty are they being made?  The answer is not consistent with how the claims are usually presented in courtrooms.

The stated purpose of the DRE protocols is only to make an arrest decision. That is, only to establish probable cause – not proof beyond reasonable doubt.

The 2018 DRE manual states the goal of the DRE officer is: “[t]he DRE’s goal is to determine the presence of impairment and the probable cause(s) of the observed impairment.”

See DRE Participant Manual, Session 6, p. 7 of 56 (2018).

12 Step Protocol

What is a Protocol?

A Drug Recognition Evaluation is a set of twelve (12) protocols. A protocol has a specific definition. If an officer is going to rely on a protocol to make a scientific conclusion, then it seems fair they should be able to generally define the term.

In science, a protocol is a predefined procedural method in the design and implementation of an experiment.

If the results of a protocol are to be successfully replicated, they must be written, standardized and specifically followed. See Hinkelmann, Kempthorne, Design and Analysis of Experiments: Introduction to Experimental Design (1994).

By Definition Then

In cases where a DRE officer did not follow the protocols, as required, they are no longer standardized.  They are no longer a protocol.  They are no longer scientific.

Failure to Follow

“The entire evaluation process is standardized.”

See DRE Participant Manual, Session 3, p. 6 of 26 (2018).

"The DEC Program simply combined those components into a systematic and standardized."

"Thus, many prosecutors believe FRYE standards do not apply to DRE evaluations and testimony." See DRE Participant Manual, Session 3, p. 22 of 26 (2018).

"Another major purpose of the preliminary examination is to begin systematically assessing the subject’s appearance, behavior, and automatic bodily responses for signs of drug‐induced impairment."

See DRE Participant Manual, Session 4, p. 10 of 50 (2018).

12-Step Drug Recognition Protocol

Breath Alcohol Test

The DRE protocol begins with a breath test. 

The test is conducted to determine whether alcohol may be causing or contributing to the impairment observed in the subject.  This is usually done by the arresting officer. 

Breath Test for Alcohol

If the subject’s signs of impairment are not consistent with the results of the test, then the officer will request a DRE evaluation.

Interview of the Arresting Officer

The DRE officer starts the process discussing the circumstances of the arrest with the arresting officer.

Officer Interview DRE

This is an attempt to find out several kinds of information (i.e. subject’s behavior, appearance, driving and any admissions about drug use). There are several specific inquiries that a DRE should make of the arresting officer.

A key concept is that the interview should be systematic. The DRE should not merely ask the arresting officer an open-ended question (“what is going with this guy?”).

Preliminary Examination and First Pulse

The primary purpose of the preliminary examination is to determine if the subject may be suffering from an injury or some other condition not related to drugs.

The DRE asks several questions relating to health, recent ingestion of food, alcohol, and drugs, and prescribed medications. The questions are a set of formal inquiries about any injuries or medical problems from which the subject may be suffering. 

  • Are you sick or injured?
  • Do you have any physical defects?
  • Are you diabetic or epileptic?
Preliminary Examination DRE
  • Are you under a doctor’s or dentist’s care?
  • Are you taking medication?
  • Do you take insulin?

The DRE is required to observe the subject’s attitude, coordination, speech, breath and face. If the officer believes that the subject may be suffering from a medical condition, the officer will seek medical assistance. However, if the officer concludes that the subject’s symptoms are drug-related, the evaluation continues.

Pulse rate is one of the vital signs that may serve as indicators of the possible presence of certain categories of drugs. However, pulse rate can also be affected by anxiety, and it is common for an arrested subject to experience anxiety while being examined by a police officer

Medical Conditions That Mimic Drug Impairment

The DRE manual recognizes that there are several medical conditions that can present the same as drug impairment:

Certain medical conditions or injuries may cause signs and symptoms similar to those of drug impairment.

See DRE Participant Manual, Session 6, p. 46 of 56 (2018).

There are times when a DRE may encounter situations where a subject arrested for drugged‐driving may be suffering from a medical condition that has affected the subject’s ability to operate a vehicle safely. If the DRE makes the determination that a possible medical issue is the likely cause of impairment (observable signs and symptoms), the DRE should consider taking the appropriate steps to ensure the subject is referred to the proper medical personnel.

A Medical Rule Out is Defined:

“A determination made by a DRE that the condition of a suspected impaired driver is more likely related to a medical issue that has affected the subject’s ability to operate a vehicle safely.”

Eye Examination

During this step of the DRE protocol, the officer gives the driver tests for horizontal gaze nystagmus (HGN), vertical gaze Nystagmus (VGN) and lack of eye convergence.

Eye Examination HGN

Prior to checking for the three clues of nystagmus, officers need to check for equal pupil size, equal tracking, and resting nystagmus.

First Clue: Lack of Smooth Pursuit. the officer is attempting to determine if the person’s eyes are moving without friction.

Examination of Eyes DRE

Second Clue: Distinct and Sustained Nystagmus

Third Clue: Angle of Onset

Lack of Convergence (LOC) means an inability to cross the eyes. The officer attempts determines whether the person can cross their eyes while focusing on a stimulus.  The stimulus is moved towards the bridge of the nose.

Lack of Convergence DRE
Divided Attention Psychophysical Tests

At this step in the DRE protocol, the officer asks the driver to take psychophysical tests known as field sobriety tests.

These tests include the:

  • Walk and Turn
  • One Leg Stand
  • Finger to Nose
  • Romberg Balance
Divided Attention Tests DRE

These tests have no correlation to impairment caused from a drug.

Walk and Turn. The Walk and Turn test is a divided attention that police clam is correlated to an alcohol concentration of .08 or greater. The test has stages in the field: (1) the instruction stage; and (2) the testing stage.

One Leg Stand. The One Leg Stand is administered twice during the DEC drug influence evaluation (one on each leg).

One Leg Stand (FSTS)

Finger to Nose. This test is used in medicine as part of a neurological examination. However, law enforcement uses a version of this test in manner that has no validity.

Modified Romberg Balance test is administered by asking the subject to tilt their head back slightly and close the eyes, and estimate 30 seconds, when they believe 30 seconds have passed, they are to tilt their head forward, open their eyes and say “Stop.”

Rhomberg Test DRE
Vital Signs and Second Pulse

Step six in the protocol calls for the DRE officer to take the driver's blood pressure, temperature and pulse (for the second time).

Vital Signs DRE

Vital signs can be raised and lowered depending on the kind of drugs the driver is taking. The protocol claims that vital signs can be used as evidence to indicate drug use.

Blood Pressure. The is no scientific evidence that blood pressure causes driving related impairment. 

Rhomberg Test DRE

Relevant Information:

  • Blood pressure and pulse rate can be affected by medications, genetics and medical conditions.
  • Blood Pressure. Ideally, systolic pressure should be less than 120. Diastolic should be less than than 80.
  • Pulse Rate. The generally accepted in the field of pharmacology that a person’s pulse rate should be between 60 to 90.
Dark Room Examinations

The DRE officer uses a device known as a pupilometer to determine if the driver's pupils are dilated, constricted, or normal.

The officer checks the eyes for their reaction to light. Some drugs increase pupil size, other drugs lower it and some drugs cause the pupils to react slowly to light changes. Also during this step, the officer checks the driver’s nasal and oral cavities for signs of drug use (such as white powder in the nose).

The principal activity that takes place during the darkroom examinations is the estimation of pupil size under three lighting conditions: (1) Room light; (2) Near-total darkness; and (3) Direct light. 

Dark room check Pupils DRE
Examination for Muscle Tone

The protocol claims that muscle can be a sign of impairment.

Muscle Tone Exam DRE

The DRE protocols state that because some drugs cause the muscles of the body to become rigid and others cause muscles to become flaccid, the DRE officer should examine the subject’s muscle tone.

Check for Injection Sites and Third Pulse

The DRE examines the driver for drug injection sites and looks for other evidence of drug injection.

The DRE protocols state that because some drugs cause the muscles of the body to become rigid and others cause muscles to become flaccid, the DRE officer should examine the subject’s muscle tone.

The DRE protocols state: “[p]ersons who frequently inject certain drugs develop lengthy scars, commonly referred to as ‘tracks,’ from repeated injections in the same veins.”

At this point, the officer takes the driver’s pulse for the third time.

Subject’s Statements and Other Observations

The DRE officer reads asks the subject a series of specific questions regarding drug use.

The DRE must carefully record the subject’s statements and any other observations that may constitute relevant evidence of drug‐induced impairment.

Analysis and Opinions of the Evaluator

The DRE officer is tasked with making an opinion based on his/her previous observations.

The DRE officer then forms an opinion about whether or not a driver is impairment based on the totality of the evaluation process.  Using the DRE Matrix, an officer must also determine what category (or categories) of drugs is causing the impairment.

Based on all of the evidence and observations gleaned from the preceding steps, the DRE should be able to reach an informed opinion as to
• Whether the subject is under the influence of a drug or drugs, and if so
• The probable category or categories of drugs causing impairment

See DRE Participant Manual, Session 4, p. 19 of 50 (2018).
Drug Recognition Evaluation Form
Toxicological Examination

The DRE requests that the driver take a urine, blood test for toxicology analysis.

A chemist can’t analyze the blood or urine and come up with a number that “proves” the person was or wasn’t impaired.

What Does This All Mean?

"Isn't An Exact Science"

Officers often present the results of their drug evaluations as a definitive answer the question of impairment and its cause.  Even the DRE Manual concedes this is not the case.

The drug influence evaluation isn't an exact
science. Drugs affect different people in different ways. In this program, we "never say never", and we "always avoid saying always".

Page 29-30
Drug Evaluation and Classification Training
Student Manual

DREs also need to understand that sometimes the toxicological analysis will not confirm the DRE's opinion. The DRE needs to be honest enough to admit that, when that happens, it may be because their opinion is incorrect.

Page 29-30
Drug Evaluation and Classification Training
Student Manual

Where did being "honest" go?

In the 2018 version of the DRE Student Manual the statement about honestly was removed.  Accordingly, it seems fair to ask the DRE officer: 

Why was honesty removed from the DRE protocol?


The Matrix

What is the Matrix?

Police claim the DRE symptom matrix is a tool that can identify the category of drug they believe is causing impairment in a driver. Keep in mind, the DRE Matrix was created by law enforcement for law enforcement goals. 


This Matrix is not used in any area of science for any legitimate scientific purpose.

Signs of Impairment & Signs of Consumption

The Seven Drug Categories

The drug categories are based largely on their common effects.

CNS Depressants

Narcotic Analgesics


Central Nervous System Depressants include drugs such as:

Carisoprodol is a muscle relaxant which includes brand names such as Soma.

Meprobamate is a muscle relaxant which includes brand names such as Miltown, Equanil, Equagesic and Meprospan.

Diazepam is a benzodiazepine which includes brand names such as Valium.

GHB (Gamma-Hydroxybutyrate) is a sedative and used as anesthetic. It can be distributed under the brand name of Xyrem.

Zolpidem is a Schedule IV controlled substance and used as a sleep aid sold under the brand name Ambien.

Ambien DUI Lawyer

CNS Stimulants

Central Nervous System Stimulants include drugs such as Cocaine.

  • Cocaine hydrochloride
  • Methylbenzoylecgonine.

Narcotic Analgesics include drugs such as:

Methadone (Methadone hydrochloride) is a synthetic narcotic analgesic and is a schedule II controlled substance.

It is prescribed for the relief of moderate to severe pain, and is also used in detoxification treatment of opioid dependence which includes brand names such as:

Dolophine, Hydrochloride, Methadose, Methadone, Hydrochloride, and Intensol.

Opiates are the class of drugs derived from opium. The psychoactive compounds in the opium include codeine and morphine (the active metabolite of codeine). 

Hydrocodone can be a metabolite of codeine when people have been using of codeine for several weeks. Norhydrocodone is the metabolite hydrocodone.

Additional opiates include: Fentanyl and Heroin.

Cannabis is the family of plants which marijuana is derived.

Cannabis contains chemicals called cannabinoids and isomers of THC (tetrahydrocannabinol)

THC’s direct metabolite is Hydroxy THC.

Hydroxy THC is further metabolized into Carboxy-THC.


LSD (Lysergic acid diethylamide) is a Schedule 1 controlled substance and psychedelic.



Ketamine is a dissociative anesthetic and a hallucinogen. In years past, it was primarily utilized as a veterinary anesthetic.

PCP is phencyclidine 


Toluene (methylbenzene, methyl benzol, and phenylmethane) is volatile solvent and CNS depressant.  However, the DRE protocols put it in the category if inhalants.

Competing Definitions

A drug is any chemical, which has an effect, when ingested into the human body.  However, the definition of a drug in the context of the DRE protocols is narrower.  The protocols defined a drug as any substance that, when ingested into the human body, will decrease the ability to operate a motor vehicle safely.

Competing Classifications

The DRE Drug Matrix’s drug classifications are distinct from the medically accepted drug classifications in pharmacology.  They are much broader.  Drug Matrix misclassifies drugs into drug categories that are not generally accepted in medicine.

DRE Drug Matrix drug categories incorrectly include different molecules and different classes of drug as one homogeneous class based largely on their common effects.

Symptoms Don't Prove Their Causes

The government claims that their Matrix of symptoms will determine the category of drug(s) that is impairing the driver.  At the same time, they use the field tests relied on in alcohol cases, as evidence of that a drug is causing impairment.

NHTSA Concedes

The National Highway Traffic Safety Administration concedes, specifically in the context of THC, there is no evidenced based method to determine if impairment was caused by a drug in an uncontrolled environment (i.e. a drugged driving investigation).

Thus, there are currently no evidence-based
methods to detect marijuana-impaired driving.

NHTSA, Report to United States Congress, p. 13 (2017). Tweet
DRE - No Evidence Based

Current knowledge about the effects of
marijuana on driving is insufficient to allow specification of a simple measure of driving
impairment outside of controlled conditions.

NHTSA, Report to United States Congress, p. 12 (2017) Tweet

Field Sobriety Tests

When alcohol is alleged to have caused impaired driving, the government claims field sobriety tests correlate to an alcohol concentration of .08 or greater – not impairment.  This claim arises from someone non-peer reviewed self-published studies.  However, the data does not support the claims.


Field Sobriety Tests

Are Not Capable of revealing drug impairment. 

When a drug (other than alcohol) is alleged to have caused impaired driving, the government uses the same field sobriety tests.  However, these test were never designed, validate nor proven to have any scientifically valid correlation to drug impairment.

Not Fit for Purpose

A primary reason these tests are not able to reveal impairment is they cannot be compared to a person’s normal performance on such agility tests. As such, these tests are not fit for the purpose of determining the cause of a persons physical symptoms.

In the DEC Program, the use of the terms “normal”, “average”, “average ranges” or “DRE average range” are often used interchangeably. There are situations where a DRE uses the term “normal” when referring to a non impaired result for a particular function or test.

Page 45 of 46, Session 4
Drug Evaluation and Classification Training Student Manual (2018)

But since the DRE does not know what
is for the individual being tested, a better and more accurate descriptor would be with the “DRE average ranges” which relate to values for healthy non impaired persons for that particular function of test.

Page 45 of 46, Session 4
Drug Evaluation and Classification Training Student Manual (2018)

 There is no hypothetical “normal” person to compare a person’s performance against.

If a DRE deems that a result is “normal” or within the “normal ranges” it does not mean the person is normal from a medical standpoint. A DRE does not make a medical diagnosis which is beyond the scope and purpose of the DRE evaluation.

Page 45 of 46, Session 4
Drug Evaluation and Classification Training Student Manual (2018)


It's Like Pornography

A DRE evaluation is scored like an pornography.  That’s right…it’s like porn.

Recall the famous United State Supreme Court case of Jacobellis v. Ohio, 378 U.S. at 197 (1964).  In Jacobellis, Justice Potter Stewart set forth how he knew something fit the criteria of pornography:

I shall not today attempt further to define the kinds of material I understand to be embraced within that shorthand description ["hard-core pornography"], and perhaps I could never succeed in intelligibly doing so. But I know it when I see it, and the motion picture involved in this case is not that.

The Weight of Each Symptom

How much weight does any specific elements of the protocol have? Moreover, do some criteria (i.e. an eye exam, pulse, or psychophysical tests) have more value than others?

Comparing DRE Findings

The answer is not defined by the DRE protocols.  Nor is any direction given, by the DRE Manual used to train officers. Under the DRE protocols. Each and every officer is free to decided for themselves whether to give more, less or equal weight any element in a DRE evaluation.

Accordingly, in the above illustration different officers – are permitted to give the exact opposite conclusions.

Generously Broad Categories

The DRE protocols have a very generous definition of an accurate prediction by a DRE. The drug categories utilized by the DRE protocols are too broad and inconsistent with what is generally accepted in pharmacology.

Shinar and Schechtman, 2005, DRE

How many symptoms?

There are more than 70 different variables associated with the DRE Program’s 12-step process. See Shinar & Schechtman, 2005. 

Each officer can give any one variable any amount of weight they chose. Thus, the protocols lack any meaningful standardization.

Definition of a Right Answer

One Right

If the DRE calls one category, that type of drug must be present in the toxicology results in order for the DRE to be considered correct.

DRE Prediction - One Drug
DRE Prediction - Two Drugs

One or Two...Right?

However, if the DRE calls two drug categories only one type of drug must appear on the toxicology report for the DIE to be considered correct, so the chance of getting at least one category right is better if the DRE calls two separate categories.

Two of Three...Right?

If the DRE calls three or more categories, then the toxicology results must identify at least two categories of the predicted drugs to be considered correct.

DRE - Three Drugs

This loose criteria incentivizes a DRE officer to call multiple categories to increase the probability their answer is considered correct.

Think about this claim

But sometimes, the toxicology doesn't corroborate a DRE's opinion even though the opinion is correct. The lab's instruments, personnel and analytical methods are not infallible. There are certain drugs that a particular laboratory simply may not test for, and there are others that can't be "seen" unless they are present at fairly high concentrations.

Page 30
Drug Evaluation and Classification Training Student Manual (2011)

How can a police officer know if they correctly related impairment to a specific drug category: if there is no toxicological confirmation?  I guess they just know it when they see it.


Supporting Studies

Bigelow Bickel, Raoche, Liebson, & Nowowieski., (1985)

Identifying Drug Intoxication, Laboratory Evaluation of a Subject Examination Procedure. [Laboratory Study].  This was the original study.  It was conducted at John Hopkins.

Not a peer-reviewed study

A different protocol used

The time provided for each evaluation was limited to 20 minutes. 

80 subjects

Randomly assigned to one of eight drugs.

Four (4) officers from the Los Angeles Police Department made the evaluations.

320 Assessments

of the 80 subjects
by the four officers.

Three Categories of Drugs:

(1) Depressants
(2) Cannabis; and
(3) Stimulants.


(CNS Stimulant)




(CNS Depressant)


15 mg


30 mg

Marijuana 12 puffs

of 2.8% THC

Marijuana 12 puffs

of 1.3% THC


15 mg


30 mg


(CNS Depressant / Barbiturate)


300 mg.

DRE officers were told that some subjects would receive no active drug

Officers were told that there would be no alcohol, PCP, LSD, or drug combinations.

Compton, R. P., (1986)

National Highway Traffic Safety Administration. Richard P. Compton, Field Evaluation of the Los Angeles Police Department Drug Detection Program, U.S. D.O.T. H.S. 807012 (1986)

Not a peer-reviewed study

It was a technical report.

84 officers

201 subjects

173 Blood Samples

Identified 13 different psychoactive substances (alcohol & 2 other drugs).

7 Categories of Drugs

PCP - was primary drug

Phencyclidine (PCP) was the most frequently detected drug being found in 56% of the suspects. It was found in 97 of the 173 samples.

Alcohol - was next most frequent

Alcohol was the next most frequently found drug at 52.6%. It was found in 91 of the 173 samples.


In only 1 of the 173 suspects

was no drugs or alcohol detected (less than 1%).


of the blood samples had

drugs and/or alcohol

Diazepam - was one of the least frequent

Diazepam was one of the least frequently found drug at 7%. It was found in 10 of the 173 samples.

Alprazolam - was one of the least frequent

Alprazolam (Benzodiazepine / brand name Xanax) was one of the least frequently found drug at less than 2%. It was found in only 1 of the 173 samples.

“The presence of THC in the driver’s blood has not been shown to be a reliable
measure of  marijuana impairment
of driving.” 

Page 13
Compton, R.P., (1986)

“There is no way to determine objectively whether the suspects were actually too
‘impaired’ to drive safely. The fact that drugs were found in a suspect’s blood does not
necessarily mean
the suspect was too
impaired to drive safely”

Page 15
Compton, R.P., (1986)

Excluded Data

Data from individuals that an officer believed where a driver was not impaired was excluded.

Adler & Burns (1994)

Conducted in Arizona to examine the work product of an their DRE Program [Field study].

Not a peer-reviewed study

185 subjects

Urine Testing

Urine testing was the primary type of toxicology test used. There were much fewer blood tests conducted.

57% Error Rate

Officers only correctly predicted toxicology findings in 43% of the subjects. See Adler, p. 34.

Heishman, Singleton, & Crouch (1996)

Claiming to test the validity of the DRE protocols for ethanol, cocaine, and marijuana [Lab study].

Until a broad range of drugs and doses are tested on the DEC evaluation and
independent performance tests under laboratory conditions, it is difficult to assess the validity of the DEC evaluation with respect to behavioral impairment criteria.

Page 13
Heishman, Singleton, & Crouch (1996)

18 subjects

Experienced drug user volunteers

9 experimental sessions

of the 18 subjects


(CNS Depressant)




(CNS Stimulant)

Such validation is critically needed, however, because the current means of confirming a DRE's prediction of impairment is the presence of parent drug or metabolite in blood or urine, which, with the exception of ethanol, provides little, if any, information
concerning behavioral impairment.

Page 13
Heishman, Singleton, & Crouch (1996)

40% Error Rate

Officers erroneously predicted that 40% of the people given placebo doses were impaired by a drug.

Heishman, Singleton, & Crouch (1998)

Testing the validity of the protocols in re: alprazolam, d-amphetamine, codeine, or marijuana [Field study].


(CNS Depressant)




(CNS Stimulant)


(Narcotic Analgesic)

A total of 162 experimental sessions. In four (4) sessions, cannabis could not be detected in confirmatory blood samples.  It was eliminated from the analyses. A double-blind drug administration procedure was then followed.

Smith, Hayes, Yolton, Rutledge, & Citek (2002)

Testing the validity of the protocols based on limited data from a simulated evaluation.

Shinar & Schechtman (2005)

Testing the validity of the protocols to detect drug impairment and identify the drug category from physical symptoms [Lab study].





The reported 76% of DRE decisions were consistent with a drug.  However, only 32% of cases was a DRE officer’s determination of drug class -consistent with the actual drug. 

If you received a placebo, then 56% of the time, the DRE technician judged you to be impaired. 

Walden (2005)

Comparing the accuracy rates of Texas law enforcement to see if they were consistent with the lab studies [Field study].

The bottom line is…

The data shows that the DRE protocols are unable accurately discriminate between drivers who are impaired and unimpaired.

There are also no studies that measure a specific DRE officer’s performance against each other – when presented with the same subjects. That is, whether or not two different officers will or will not get the same results for the same subjects. 


Statistical Flaws

A DRE examination is simply a kind of screening test. The accuracy of a screening test is determined by its sensitivity and specificity.  However, DRE claims are commonly made without this kind of statistical analysis.

Screening Tests

Here, the screening test is a diagnostic test (i.e. the results of physical examinations).  Generally comparing the results of a screening test to – a lab result – does not define the accuracy of such diagnostic tests.  This type of calculation is too blunt and produces misleading conclusions.

Sensitivity & Specficity of DRE

Sensitivity & Specificity

It is generally accepted in the field of statistics that the usefulness of a screening test is determined by its sensitivity and specificity. Reliable and valid screening tests are both sensitive and specific.

Sensitivity is the test’s true positive rate.  Sensitivity measures how many subjects with the condition – actually test positive for it.  Tests that are highly sensitive, but not specific, produce greater amounts of false positives.

Sensitivity of DRE

Example: Your car alarm should go off when someone, who does not have your permission, attempts to enter your car.  A parked car’s alarm, that goes off whenever someone walks within fifty (50) feet of it, is overly sensitive

That is because not everyone who walks within fifty (50) feet of your car is intending to break into it.

The data underlying the DRE protocols demonstrates that they are (just like that car alarm) – overly sensitive.

Specificity is the proportion of subjects without the actual condition who have a negative test result. It is the test’s true negative rate. It measures how many people without the condition – incorrectly test positive for the condition.

Specificity of DRE

Highly specific screening tests result in a low percentage of false positive results. The data underlying the DRE protocols show that they are not specific enough to justify their claims.

Individual Officer's Sensitivity & Specificity

The importance of determining sensitivity and specificity does not stop when evaluating the DRE protocols validation studies.  These metrics are essential to determining whether any individual DRE officer’s results have any validity.  That is, are they reliably measuring what they claim to measure?

DRE Officer's Accuracy Log

DRE officers are required to  maintain a “rolling” log of individuals they have evaluated and maintain a minimum accuracy rate.  However, how do they determine an officer’s true accuracy rate?

The methodology of used by police officer to determine if they have maintain a minimum accuracy rate is by comparing hits and misses.  That is, simply comparing the number an officer’s opinion in an evaluation to that matched the toxicology results to the cases where there were they did not match.

An Officer's Results

Step 11 in the DRE protocol requires an officer to make an opinion whether the driver is impaired.  If so, the officer must also predicted what category (or categories) of drug(s) is causing that impairment. This raises the question: how do we test the accuracy any DRE officer’s results?

DRE Officer’s Log

We start by looking at a DRE officer’s Rolling Log. This log records the results of each DRE officer’s evaluations compared to the corresponding toxicology results.

What is relevant to the proper analysis is the underlying data in the log – not what the government’s claimed accuracy rate.  The required statistical analysis is looking at the officer’s sensitivity and specificity when applying the DRE protocol.  The officer’s specificity it particularly relevant.

Required Questions

How many subjects evaluated - had no drug in their body?

How many subjects evaluated - did the officer claimed impaired by a drug - when no drug was in their body?

What is the officer's false positive rate (a measure of specificity) ?





Chemical Testing

In DUI case alleging drug impairment – the natural assumption of most people is that the results of a chemical test determine innocence or guilt.  This is a false premise the requires deconstructing.


All chemical test results

Are not capable of determining drug impairment

This includes measurements of drug concentrations in blood conducted using gas chromatography mass spectrometry (GCMS).

But, don’t take my word.

CAVEAT INTERPRETOR! As man does not live only by bread, so the toxicologist cannot interpret his results by numbers alone...

Dr. Irving Sunshine, Manual of Analytical Toxicology
Sunshine - Caveat Interpretor
NHTSA - NO chemical Test for THC

This includes the fact that there is no chemical test for marijuana impairment, like BAC or BrAC test for alcohol that quantifies the amount of alcohol in their body indicates the degree of impairment...

NHTSA, Report to United States Congress, p. 13 (2017).

Blood testing is considered the “gold standard” for testing for the presence of drugs in impaired driving cases. However, as described in the background section to this report, currently there is limited ability to relate the amount of a drug or metabolite in blood to the presence and amount of impairment...

NHTSA, Report to United States Congress, p. 10 (2017).

Based on this analysis, a quantitative threshold for per se laws for THC following cannabis use cannot be scientifically supported.

An Evaluation of Data from Drivers Arrested for Driving Under the Influence in Relation to Per Se Limits for Cannabis.

AAA Foundation for Traffic Safety.

Therefore, this means...

You can have a significant concentration of THC in your blood and none in your brain.

Blood Test Result:

5 ng of THC 

DOES NOT equal impairment.

of blood drawn from your arm.

Blood Test Result:

10 ng of THC 

DOES NOT equal impairment.

of blood drawn from your arm.

Blood Test Result:

20 ng of THC 

DOES NOT equal impairment.

of blood drawn from your arm.

Keep in mind, it is certainty possible to be impaired when there is a concentration of a drug in your blood.  However, this information is simply inadequate to make such a conclusion.  More information is required.

But why?

Stating a scientific fact to a judge or jury – as a premise for the conclusion you want them to accept – is not always enough to persuade. You must show them why your premise is true.

An Unpredictable Correlation


Alcohol is hydrophilic. It has an affinity to seek water. After consumption, it makes its way to your lungs and eventually into your bloodstream.  This results in a predictable correlation between a concentration of ethanol in your blood and the brain.

Blood Drug & Brain Correlation

Thus, measuring the concentration of alcohol in a blood sample taken from a person’s limb provides trustworthy evidence of the ethanol concentration in a person’s blood.

The body also has predictable reactions to ethanol if the concentration is high enough.  These facts provide a sound basis for the opinion that there is universal impairment at .08 ng/ml.

Arizona Marijuana Laws

However, in the case of other there is no such correlation. For example, in drugs like THC:

THC is fat-soluble. It is absorbed differently than alcohol by your body. As a result, it is difficult to relate physical effects to a concentration of the drug in the blood. 

THC Concentration correlation

The bottom line

A chemical test, in and of itself, is not capable to revealing if impairment is caused by a drug.


Discovery Requested

What do you want to see to deconstruct DRE drugged driving claims?  Here is a start:

Any and all evaluations, proficiency examination checklists, field examination grades and test scores for the DRE officer.

Any and all proficiency testing documented in the officer's certification program (recertification is required every two years).

The DRE officer's "rolling log" documenting all of his drug influence examinations from the time of certification to the time of the this request.

Any and all documentation for this DRE evaluation.  This includes, but is not to, the "face sheet," all notes and reports for this DRE evaluation. 

The DRE officer's IACP (International Association of Chiefs of Police) certification number.


Big Take Aways

The DRE claims are based on junk statistical methods.

When the necessary statistical analysis is applied to the underlying data it shows the protocol is overly sensitive and lacking specificity.

Field Sobriety Tests Do Not Measure Impairment.

The agility tests do not correlate to drug impairment or driving performance.

Chemical test results don't revealing if drugs are causing impairment.

Chemical test results (including blood tests using GCMS) are not capable of determining drug impairment.

Tolerance does not equal addiction or dependence

The degree of tolerance to a drug varies from person to person.

A concentration above a therapuetic limit does not equal impairment.

A test result above the upper limit of a therapeutic level does not equal impairment.

The presence of an active drug does not mean it is impairing you.

Unlike alcohol, there is not a reliable correlation between a drug concentration in the blood and the concentration in the brain. Thus, having an active drug in your blood does not mean the drug is impairing you.

Drug DUI | Drugged Driving | DRE | Arizona DUI

Frequently Asked Questions

  1. whether a person is impaired
  2. Which category or combination of categories of drugs is the most likely source of the impairment?
  3. Is the person able to operate a vehicle safely?

According to the Arizona Governor’s Office of Highway Safety (GOHS), the goal Arizona’s Drug Evaluation Program is to “train and certify law enforcement personnel as Drug Recognition Experts (DREs).”

The International Association of Chiefs of Police (IACP) regulates and is the credentialing organization for the Drug Evaluation Program.

An officer’s DRE certification lasts 2 years.

  1. Cannabis (marijuana)
  2. Central Nervous System (CNS) Depressants
  3. Central nervous system (CNS) Stimulants
  4. Hallucinogens
  5. Inhalants 
  6. Narcotic Analgesics
  7. Dissociative Anesthetics.

1. A breath alcohol test;

2. An interviewing;

3. Obtaining an initial pulse rate on the subject;

4. Eye examinations;

5. Four divided attention tests (Romberg Balance, Walk and Turn, One Leg Stand, Finger to Nose);

6. Vital signs and a second pulse rate;

7. analyzing the subject’s eyes and pupil size in dark and light conditions and examining the subject’s nose and mouth for evidence of ingestion of drugs;

8. checking the subject’s muscle tone to determine if his muscles are rigid, normal, or flaccid;

9. examining the subject for evidence of injection sites and obtaining a third pulse rate;

10. interrogating the subject about what drugs he has ingested;

11. formulating an opinion about whether the subject is impaired and what categories of drugs are responsible for the impairment; and

12. Toxicological Examination.


The program was developed by police officers from the Los Angeles (California) Police Department in the early 1970s. The officers’ drug recognition methods were officially recognized by the LAPD management in 1979 and adopted by the National Highway Traffic Safety Administration in the early 1980s.  Officers with no formal scientific training enroll in a 72‑hour course designed to teach them about the effects of seven different categories of drugs on the body. Officers are taught to administer a twelve‑step drug evaluation and classification protocol. The entire test lasts approximately 45 minutes to an hour.

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