DRE Training Notes: Preliminary Interview, Eye Examinations, Psychophysical Tests, and Evidence Handling
Preliminary Interview and Information-Gathering
The session emphasizes gathering a complete picture of the incident by interviewing the arresting officer, the officer who conducted the dose/field tests, and anyone who can provide relevant information. Interviewers should use the CHP form as a starting point but must avoid mechanical, checkbox-driven questioning. The goal is to obtain the full story, including what happened when the interviewer wasn’t present. If the interviewer was on the scene, they have more information to corroborate, but even then they should pull details from others to fill gaps. The example given describes a stop for a red light, detection of burnt marijuana in the car, a post-opa tirating test (likely a field or preliminary test) suggesting cannabis impairment, and an arrest, illustrating the type of information to extract deeply rather than superficially.
Key elements to probe include: whether the subject reported illness or injury, the exact location and circumstances of the stop (e.g., whether the driver allegedly ran a yellow light or sped through a yellow phase), what the officer smelled, the initial contact and demeanor of the subject, and whether any paraphernalia was found in the vehicle. Important is to determine what the officer observed (clues, signs of impairment) and what statements the subject made about actions, substances, or impairment. Asking about the subject’s illness or medical issues helps rule out medical conditions that could mimic impairment. When the subject wasn’t there, you must extract specifics about their behavior, decisions, and substances used.
You should also explore the subject’s past intake of substances, including what was used, how it was used, and when the last use occurred. This includes whether the subject smokes marijuana, uses edibles, or uses prescription medications, as well as the dosage and whether the subject has a prescription. In addition, inquire about how recently any meds were taken (with bottle present if possible), which helps establish timing and potential interactions with impairment tests. The investigator should document medical issues that could affect performance on tests (e.g., diabetes, hypoglycemia, stroke, seizures) and confirm whether the subject has seen a doctor recently and whether medications might influence impairment. This information supports guarding against defenses that a medical condition, rather than impairment, caused the observed behavior.
Questions should aim to uncover specifics, not merely confirm a yes/no answer. For example, instead of asking whether the person last used marijuana, ask how they used it (smoked, vaped, edibles), how long ago, how much, and what form (blunt, pipe, etc.). In the case of prescription drugs, ask what was prescribed, the last dose, and whether a bottle is present to verify the prescription and label directions. The trainer emphasizes the importance of engaging with the subject respectfully and as a human being — this helps elicit more candid responses and a richer information set for later correlation with objective signs and test results.
Another practical point is documenting consent for samples when toxicology is involved. California’s GSP 67 is noted for governing drug testing and consent, including options for breath or blood. Even when consent is given, you must follow department policies for handling samples and ensure the samples are properly stored and not left in the field. Miranda warnings are also referenced as part of obtaining statements and building a complete, legally sound case based on the totality of the circumstances, not a single clue.
Overall, the purpose of the preliminary interview is to gather as much objective and subjective information as possible so that later testimony (STATEMENTS, signs, and test results) can be connected coherently. The emphasis is on depth, specificity, and consistency with observed signs and the totality of the circumstances, rather than rushing to conclusions based on limited data.
Scene Information, Location, and Initial Observations
Interviewers should establish concrete details about the scene: the exact location, whether the area is busy, and the conditions at the time of the stop. Clarifying how the red-light event occurred (whether the driver accelerated aggressively, barely made the light, or the light stayed yellow for an extended period) helps distinguish impairment-related driving behavior from ordinary driving. Observations at the scene include what was smelled (e.g., burnt marijuana), what information the officer had prior to contact, and how the initial contact unfolded (cooperative or resistant demeanor). The presence of paraphernalia, drug-related residues in the vehicle, or other physical evidence should be documented as early clues.
Additionally, the officer’s statements about what happened prior to the contact (e.g., stopping a car for a red light, smelling burnt marijuana, and performing a post-ops test) should be captured and cross-checked with the driver’s reported history and subsequent test results. This helps with constructing a narrative that links objective evidence with subjective statements, which is critical during the later stages of the DRE evaluation and any resulting testimony.
Medical Screening and Physical Defects
A key component of the preliminary interview is ruling out medical conditions that could mimic impairment. The interviewer should inquire about illnesses or injuries and probe deeper for medical issues that might affect balance, coordination, or cognitive function. The goal is to identify issues such as diabetes with hypoglycemia, stroke, or seizures, which could complicate or invalidate certain field tests if not appropriately ruled out.
Examples provided include ruling out diabetic episodes and ensuring no acute medical issue is present that would explain abnormal test results. If a subject claims a physical defect or pain (e.g., back injury), the interviewer should press for specifics, such as duration, onset, and current treatment, along with any medications. This helps anticipate defensive arguments that a medical condition affected performance on tests and ensures the interviewer can document the absence or presence of conditions with sufficient detail for later cross-examination.
Asking about medications and substances is crucial. The interview should cover both over-the-counter drugs and prescribed medications, including dosage, timing, and whether the subject possesses the medication bottle. This information helps assess potential impairment due to medication interactions or recent dosing, and it supports the later interpretation of test results in light of potential pharmacological effects.
Importantly, the trainer stresses not treating questions as mere checkbox items. Instead, ask specific follow-up questions that reveal context and timing (e.g., last use, dose, method of ingestion, and whether a prescription was filled recently). If a subject reports marijuana use, the interviewer should query how they used it, how long ago, and how much they used, including details such as edibles, smoking methods, or vaping, to build a timeline that can be correlated with observed impairment signs.
Vital Signs and Immediate Assessment
Within the preliminary examination, vital signs are introduced as an essential part of building a comprehensive profile. The first pulse should be recorded, with a note of the time it occurred, to establish a baseline and track changes across the evaluation. A second pulse and a blood pressure reading are also recommended as part of the ongoing assessment, along with temperature measurements when available. The temperature probe should be used with proper hygiene and protective equipment (gloves, disposable sleeves) to reduce cross-contamination and maintain safety during contact with the subject.
The order of operations for biological samples and tests is discussed in relation to the timing of cannabis impairment. Because THC from cannabis can become detectable quickly after inhalation, it is indicated that cannabis testing should occur at the beginning of the assessment to capture active impairment, while other tests and samples can follow. The discussion also covers the need to balance rapid assessment with safety and protocol for collecting samples, emphasizing the importance of following agency policies for evidence handling and consent procedures.
Eye Examinations and Pupillary Assessment
The eye examination is a central component of the DRE process. The preliminary stage includes an initial check of the eyes, assessing pupil size, reaction to light, and the presence of resting nystagmus. After establishing initial measurements, the formal eye examination proceeds with the Horizontal Gaze Nystagmus (HGN) assessment and the pupillometry procedure in two settings: room light and near-total darkness.
Key steps include: establishing room-light pupil sizes for both eyes; conducting the HGN with two passes per eye to ensure reliability, and confirming the absence or presence of resting nystagmus and equal pupil sizes. The difference between natural and drug-induced nystagmus is considered, with an expectation that most individuals will be aware if they have natural nystagmus. The examiner should be alert to asymmetries in pupil size that could indicate injury or neurological issues.
In the dark room, the pupillometer is used to measure pupil size in near-total darkness (to assess CNS depressants or stimulant effects) and with direct light. The procedure includes keeping the subject in near-total darkness for approximately , then shining a light from behind the head to illuminate the pupil only within the eye socket, avoiding glare on the face. The examiner records four measurements: left eye in ambient light, right eye in ambient light, left eye in direct light, and right eye in direct light. These measurements are essential for interpreting impairment, but they are not diagnostic of a specific drug category; they contribute to the overall picture of impairment and aid in linking signs to alleged substance use.
When conducting the dark-room assessment, the examiner must maintain officer safety and follow department policies about entering the space. The use of a dim room, proper positioning relative to the suspect, and ensuring the light is angled appropriately (not directly into the eye) are emphasized to obtain accurate pupillary readings without provoking resistance or discomfort unnecessarily.
Diagnostic Clues and Evidence Correlation with Psychophysical Tests
Beyond the ocular examination, the DRE process includes assessing nostrils, mouth, teeth, and lips for signs of inhalant use or other drug consumption. Observations such as nasal irritation, residue, redness, or damage to the septum can indicate chronic inhalant abuse or high-frequency smoking. The mouth and teeth can reveal “meth mouth” or other drug-related damage. The examiner looks for muscle tone (flaccid vs. rigid), injection sites, track marks, and other signs of drug administration that could corroborate impairment.
In addition to physical signs, the interviewer should engage the subject in conversation to understand drug history and methods of administration. This includes asking about the first drug use experience, gateway drugs, age of first hard drug, and general experiences with drug use. The purpose is to obtain information that helps contextualize the impairment while maintaining professional, respectful communication. This conversation provides a broader understanding of the subject’s drug history and potential patterns of use that may inform the interpretation of current testing results.
These clues are then integrated with the totality of evidence: subjective statements, objective signs, vital signs, and psychophysical test results. The objective is not to force a drug category from a single cue but to form a well-supported impairment assessment that aligns with the most relevant drug class guidance. The DRE report should explicitly relate observed clues from the psychophysical tests (e.g., nystagmus directions, gait deficits, balance errors) to the officer’s on-scene observations, to demonstrate a coherent chain of reasoning that supports the driver’s impairment status.
Psychophysical and Divided-Attention Testing (The Four Tests)
The program outlines four standardized divided-attention psychophysical tests used to gauge impairment: the Modified Romberg, Walk-and-Turn, One-Leg Stand, and Finger-to-Nose. These tests are designed to reveal impairment but do not themselves diagnose a specific drug; they indicate impairment and help narrow the field to the impairment level and potential categories when combined with other evidence. The instructor emphasizes completing each test with proper instruction and documentation of clues observed during each test, which will form the basis of the impairment narrative in the DRE report.
During the HGN and psychophysical testing, instructors stress the importance of accuracy and pacing. For example, the two passes per eye for the HGN should be performed to ensure reliable observation of nystagmus at different gaze angles. For the Romberg, the walk-and-turn, the one-leg stand, and the finger-to-nose, the examiner should carefully observe and record clues such as balance, coordination, gait, and accuracy of movements. Clues are not used in isolation to assign a drug category; rather, they support the impairment assessment and help correlate subjective reports with objective findings.
The instructor reminds students to avoid rushing through the tests and to use precise language when describing clues and impairment. The end goal is to tie the psychophysical clues to the impairment and potential drug category, and to reference these clues in the report in relation to the officer’s statements about the incident. Importantly, the instructor underlines that impairment is not exclusive to a single drug class; impairment exists with alcohol, cannabis, inhalants, stimulants, depressants, and other substances, and the tests help to characterize the degree of impairment and its potential source.
Drug Testing, Consent, and Evidence Handling
The DRE training explicitly covers toxicology with a focus on consent and evidence handling. The subject should be informed about the option of breath or blood sampling for chemical analysis, and investigators must comply with state consent laws (e.g., GSP 67 in California). If the subject consents to breath testing, additional samples for blood may be requested if drug impairment is suspected. The collection and handling of samples must follow agency policy to ensure the integrity and admissibility of evidence. It’s noted that samples should not be left in a car or mishandled; proper chain-of-custody and packaging are essential.
Miranda rights and voluntary statements remain a separate track from the physical impairment assessment. Statements obtained during the process should be connected to the totality of the circumstances and not over-relied upon as a sole basis for impairment classification. The training emphasizes the need for thorough documentation and careful correlation between observed signs, test results, and statements made by the suspect and the arresting officer. The key takeaway is to build a cohesive narrative that withstands scrutiny in court by linking the subject’s actions, the officer’s observations, the psychophysical test results, and the toxicology findings within the framework of the law.
Safety, Training, and Professional Practice
The session concludes with emphasis on officer safety and professional conduct. The DRE program aims for high standards of verbiage, instruction, and test administration, while maintaining safety for officers and suspects. Training is framed as a two-week intensive program that prepares students to execute the 12-step process with precision while adhering to ethical and legal constraints. The instructor encourages students to practice regularly, develop accurate and confident opinions, and approach the process as a life-saving responsibility rather than a routine procedure. Safety considerations include not entering a dark room alone, knowing department policy on handcuffing, and using appropriate protective measures (gloves, proper handling of instruments, and careful lighting procedures during eye exams).
Finally, the instructor reinforces that the DRE process is iterative and improves with repetition, practice, and attention to detail. The goal is to ensure that by the end of training, students can perform the 12-step procedure with clarity, safety, and confidence, and to deliver testimony that accurately reflects impairment, its cause, and its correlation to observed signs and test results. The closing message emphasizes study, dedication, and the real-world impact of trained, responsible DRE practice on protecting the public and saving lives.
Summary of Key Quantitative and Process Details (LaTeX-format)
- On-scene red-light stop with odor of burnt marijuana and post-oc eting test leading to arrest: ext{red-light stop}
ightarrow ext{odor observed}
ightarrow ext{initial test}
ightarrow ext{arrest}. - Preliminary questioning targets medical issues: ext{illness/injury}
ightarrow ext{rule out medical issue}
ightarrow ext{statement collection}. - Scene dynamics and vs. impairment cues: ext{yellow light duration}
ightarrow ext{driver behavior assessment}. - Cannabis impairment timing emphasis: cannabis testing at the beginning due to pharmacokinetics of after inhalation.
- Time-sensitive pulse and vitals: first pulse at time , second pulse at time , with to assess physiological changes; blood pressure and temperature readings are integrated into the impairment assessment.
- Eye examination sequence: HGN with passes per eye; pupillometry in ambient light vs near total darkness (with a dark adaptation period), and direct light measurements for four readings: left ambient, right ambient, left direct, right direct.
- Pupillometer measurements recorded as four numbers in two conditions: ambient vs direct light for each eye, plus differences between room and dark conditions.
- The 4 psychophysical tests (divided attention):
- Prohibited or cautionary practices: never shine the light directly into the eye in an extended duration; avoid leaving samples in the car; maintain officer safety and departmental policy adherence; ensure Miranda rights and consent laws are followed.
- Critical timing and distance references for testing: pupil measurements and test instructions require precise distances (e.g., for alignment) and timing (e.g., center-to-nose movement for instruction, and the standard practice of two passes for each eye in HGN to ensure accuracy).
- Spatial positioning for officer safety and test administration, including maintaining awareness of weapon side and presenting the subject to a safe direction during testing, with practice recommendations to achieve consistent, repeatable results.
Note
This set of notes consolidates the detailed instructor guidance from the transcript into a structured reference for study and exam preparation. It covers the interview approach, scene information, medical screening, vital signs, eye examinations, psychophysical tests, toxicology considerations, and safety protocols, with a strong emphasis on connecting observed signs to impairment within the totality-of-the-circumstances framework and the 12-step DRE process.