Intro. to drugged driving

10.2 Introduction to Drugged Driving[1]

This class covers the 7 categories of drugs, and an overview of polydrug use.

“From the perspective of traffic law enforcement, a non-medicinal concept of "drug" is needed. The definition we will use is adapted from the California Vehicle Code, Section 312:

A drug is any substance, which when taken into the human body, can impair the ability of the person to operate a vehicle safely[2].”

There are 7 categories of drugs.


10.2.1 Depressants


“Central Nervous System Depressants: This category includes a large number of different drugs, all of which slow down the operation of the brain and other parts of the central nervous system (CNS). The most familiar drug of all--alcohol--is a central nervous system depressant[4].

CNS depressants slow down the operations of the brain. They usually depress the heartbeat, blood pressure, respiration and many other processes controlled by the brain[5].”


Alcohol,Rohypnol, Anti-Anxiety Tranquilizers (e.g., Valium, Xanax), Barbiturates, Muscle relaxants, Many Others

General Indicators

"Drunken" behavior, Uncoordinated,  Drowsy, Eye Indicators,Sluggish, Disoriented, Thick, Slurred Speech

Horizontal Gaze Nystagmus generally present.

Vertical Nystagmus possibly present.

Pupil size usually normal (except that the drug Methaqualone and Soma  usually cause pupils to dilate)[6].”


10.2.2 Stimulants


“Central Nervous System Stimulants: This category also includes a large number of drugs, all of which act quite differently from the depressants. Central nervous system stimulants impair by "speeding up", or over-stimulating the brain. Cocaine is an example of a CNS stimulant[7].”

Action “CNS stimulants accelerate the heart rate and respiration, elevate the blood pressure, and "speed up" or over-stimulate many other processes of the body.



Cocaine, The Amphetamines (e.g.,dextroamphetamine, amphetamine sulfate, etc.), Methamphetamine,

General Indicators

Restlessness Grinding Teeth (Bruxism), Talkative Redness to Nasal Area (if "snorting"),

Excitation Runny Nose (if "snorting"), Euphoria Body Tremors, Exaggerated Reflexes Loss of Appetite,

Eye Indicators

Nystagmus generally will not be present.

Pupils generally will be dilated.[8]



10.2.3 Hallucinogens





“HallucinogensThis category includes some natural, organic substances, and some synthetic chemicals. All hallucinogens impair the user's ability to perceive the world as it really is. Peyote (which comes from a particular variety of cactus) is a naturally-occurring hallucinogen. LSD is an example of a synthetic hallucinogen[9]

“Action: Hallucinogens may cause hallucinations, i.e., they cause the user to perceive things differently from the way they really are.


Peyote (derives from cactus), Psilocybin (derives from mushrooms), LSD,  MDA,

MDMA (Ecstasy), Many Others

General Indicators

Hallucinations, Dazed Appearance, Body Tremors, Uncoordinated, Perspiring, Eye Indicators,

Disorientation, Paranoia, Difficulty in Speech, Nausea, Piloerection (goose bumps)


Nystagmus generally will not be present.

Pupils generally will be dilated.


10.2.4 Dissociative Anesthetics


“Dissociative Anesthetics This category consists of the drug PCP and its  various analogs (or "chemical cousins") and Dextromethorphan (DXM). “Originally developed for use as an anesthetic, PCP is a powerful drug that in some ways acts like a depressant, in other ways like a stimulant, and in still other ways like an hallucinogen. Ketamine is an analog of PCP[10].”



Dissociative Anesthetics are powerful anesthetics. However, they also cause bizarre and sometimes violent behavior.

General Indicators

Perspiring Blank Stare, Repetitive Speech Incomplete Verbal Responses, Confused Muscle, Rigidity, Possibly Violent and Combative


Eye Indicators

Horizontal gaze nystagmus generally will be present, often with early onset.

Vertical nystagmus generally will be present.

Pupil size generally normal.[11].”


10.2.5 Narcotic Analgesics


“This category includes the natural derivatives of opium, such as morphine, heroin, codeine and many others. The category also includes many synthetic drugs, such as demerol, methadone and others. All narcotic analgesics relieve pain (that is what "analgesic" means) and produce addiction[12].”

“Action: All narcotic analgesics share three important characteristics: they relieve pain; they produce withdrawal signs and symptoms when the drug is stopped after chronic administration; and, they suppress the withdrawal signs and symptoms of chronic morphine administration


Morphine Fentanyls, Heroin Demerol, Codeine Methadone, OxyContin, Many OtherOpium Derivatives, Synthetic Opiates

General Indicators

"On the Nod" Facial Itching, Droopy Eyelids Low, Raspy Speech, Depressed Reflexes, Fresh Puncture Marks May Be Present, Dry Mouth Evident

NOTE: A tolerant user who has taken their "normal" dose of narcotic analgesic may not exhibit these general indicators.

Eye Indicators

Nystagmus generally will not be present.

Pupils generally will be constricted.[13]


10.2.6 Inhalants


‘InhalantsThis category includes many familiar household materials such as paint, model airplane glue, aerosol sprays, etc. None of these  substances is manufactured for use as a drug. However, they produce volatile fumes that can produce significant impairment, and they are abused by some people[14].”

“Action Some inhalants include psychoactive chemicals that produce a variety of effects. Others exert their major effect by blocking the passage of oxygen to the brain.



Volatile Substances (glue (toluene), paint, gasoline, many others), Aerosols (hair sprays, insecticides, many others), Anesthetics (nitrous oxide, ether, chloroform, etc.)

General Indicators

Disorientation, Confusion, Slurred Speech, Possible Nausea, Possible residue of substance on face, hands, clothing.


Eye Indicators

Horizontal gaze nystagmus generally present.

Vertical nystagmus possibly present.

Pupil size generally normal.[15]



10.2.7 Cannabis


CannabisThis is the category that includes marijuana hashish, as well as synthetic compounds[16]. “

“Action: Marijuana and other Cannabis products impair the attention process. Ability to perform divided attention tasks diminishes under the influence of Cannabis.


Marijuana Marinol, Hashish Dronabinol, Hash Oil

General Indicators

Reddening of Conjunctiva Disoriented, Body Tremors Relaxed inhibitions, Odor of Marijuana Difficulty in Dividing Attention

Eye Indicators

Nystagmus generally will not be present.

Pupil size will generally be dilated, but sometimes can be normal. [17]


10.2.8Pupil Size

” Subjects under the influence of narcotic analgesics generally have constricted pupils. Subjects under the influence of CNS stimulants or hallucinogens generally have dilated pupils. Cannabis generally causes pupil dilation. Most CNS Depressants, Dissociative Anesthetics and Inhalants generally leave pupil size within the normal range.[18]

Horizontal Gaze Nystagmus generally occurs with subjects under the influence of three categories of drugs of three categories of drugs (DID):

CNS depressants (including alcohol)


Dissociative Anesthetics

The nystagmus generally will be present with a very early angle of onset. Resting nystagmus may be evident especially with high doses. That is a distinct jerking of the eyes even as the suspect stares straight ahead[19].” However, resting nystagmus can also be a medical problem[20].

“Vertical nystagmus usually occurs with Dissociative Anesthetics, and may occur with relatively high doses of CNS depressants or inhalants. [21]


10.2.9Polydrug Use

“In general, any combination of drugs may act together in four general ways.

Null - Neither drug has an effect on the indicator.

Null Effect: The combination of no action plus no action equals no action.

EXAMPLE OF NULL EFFECTS: CNS Stimulant and Narcotic Analgesic.

Neither drug causes nystagmus, there-fore you will not see nystagmus with this combination.


Overlapping - Each drug may affect the suspect in some different way. In combination, both effects may appear.

Overlapping Effect: Action plus no action equals action.

EXAMPLE OF OVERLAPPING EFFECTS: Dissociative Anesthetic and Narcotic Analgesic. Dissociative Anesthetic will enhance nystagmus, while a Narcotic Analgesic does not cause nystagmus. There-fore, you will see nystagmus.

Additive - The two drugs may independently produce some similar effects. In combination, these effects may be enhanced.

Additive Effect: Action plus the same action reinforces the action.

EXAMPLE OF ADDITIVE EFFECTS: Stimulants and Hallucinogens both cause pupil dilation. Pupils would be dilated.


Antagonistic - The two drugs may produce some effects that are exactly opposite. In combination, these effects may mask each other.

Antagonistic Effect: Action versus opposite action can’t predict the outcome.

EXAMPLE OF ANTAGONISTIC EFFECTS: A CNS Stimulant usually causes pupil dilation, a narcotic usually causes constriction. It is possible that someone who is simultaneously under the influence of a stimulant and a narcotic may have pupils that are nearly normal in size. It is also possible that the suspect's pupils may be dilated at one time, and then become constricted, as the effects of one drug diminish while the effects of the other increase.[22]


[2]Id at 2

[3] All images in this chapter are originally by NHTSA in various publications, are in the public domain, and are not Copyrighted. If you want to have fun with the officer, maybe you can ask him if the driver looked like the image in its respective category.

[4]Id at 2

[5]Id at 5

[6]Id at 6

[7]Id at 2

[8]Id at 6

[9]Id at 2

[10]Id at 2

[11]Id at 6--8

[12]Id at 2

[13]Id. at 8

[14]Id. at 3

[15]Id. at 10-11

[16]Id. at 2-3

[17]Id. at 11

[18]Id. at 6

[19]Id. at 7

[20]Id at 6


[22]Id. at 10-11