DWI investigations: How officers can capitalize on the driver interview to gather evidence

Maximize your effectiveness by laying on the charm and practicing patience in this stage

This is the second article in a series that focuses on tips, techniques and methods front-line officers can use to improve their intoxicated driving interdiction abilities. Click here to read the first article.

Personal contact is the phase in DWI investigations when officers will derive most of the evidence of intoxication. Based on my experience, I find most officers tend to spend far too little time and effort during this phase. This phase is the most challenging because it can require an immense amount of patience. To be an effective intoxication investigator you must be patient, charming and sensible.


While interviewing the violator, always keep your senses keen for other indicators of impairment such as open containers, pill bottles, narcotics or paraphernalia, wristbands and bar receipts. Use your nose. Odors or lack thereof need to be noted.

This phase is the most challenging because it can require an immense amount of patience.
This phase is the most challenging because it can require an immense amount of patience. (Getty Images)

If the person presents with drunk-like behaviors but you do not smell any alcohol, this could be a sign of a medical issue or drug impairment. Do you smell marijuana? Despite what many may think, cannabis is an impairing substance.

Relying on a basic and fundamental policing concept, watch the violator’s hands. Are they fumbling for their information? Do they have difficulty operating the seatbelt mechanism, opening the glovebox or interacting with the environment of the vehicle?


When it comes to the interview, one technique I have always employed is borrowing the divided attention concept from standardized field sobriety tests (SFSTs) and applying it to this phase of the investigation. When violators are asked to produce requested information, sometimes they will dig around for it; this presents a perfect opportunity to begin dividing their attention to see if they can still function effectively.

While they are fetching the requested information, start asking relatively easily answered questions and gauge their responses. Do they stop searching for the items and have to think about their answers? Do they automatically start searching for the items again or do they forget? Continue this type of questioning while dividing their attention.


Don’t be afraid to ask irrelevant questions like “Where do you go to church?” or “Are you a sports fan?” These are questions that people who have the normal use of their mental and physical faculties can answer with relative ease. This also allows you to establish a baseline of response behavior since the questions are seemingly irrelevant and would give them no reason to lie.

A bonus with these kinds of questions is you begin to establish rapport with the individual. Avoid following a script and instead be fluid and dynamic during the conversation. Do not be afraid to make a joke or show your personality a little.

One of the biggest mistakes officers make during this phase is not allowing the violator to speak or shutting them up so the officer can ask the next question. Sometimes the officer will become argumentative and accusatory, which will only cause the violator to shut down. Exercise patience and avoid being these types of officers.


If the violator wants to talk to you, let them. Doing so extends the time you have to detect impairment, gather evidence and capture the signs and symptoms of impairment on video. Good rapport leads to cooperation; the more cooperative a person is the easier your job becomes and the more evidence you will gather.

All of this will matter during a trial because jurors will see you as a polite, firm-but-fair and relatable officer instead of an authoritative robot. If the violator likes you and the jury likes you, then you are in good shape.

It is a good idea to ask about medical issues or physical limitations early on in your questioning. If you ask these questions right before you administer SFSTs, the violator may claim every ailment known to man to justify any potential poor performance. By asking the questions early on, you can call them out on it if they claim an ailment later, and the jury will see it for what it is.

Also, if you ask a question and they provide an inadequate answer, repeat the question until they provide an answer (i.e., “Do you have the time?” The answer would either be yes or no).

Another tactic I like to use is to ask the same or similar questions multiple times to see if their answers change; you will be surprised by some people. Normally, I play this off by acting forgetful or distracted, and I usually do this after the first round of questioning but before transitioning to pre-arrest screening. You can also repeat each answer back to the violator to make sure their statements are clearly captured on audio.


One good ending question to ask before starting a pre-arrest screening is “On a scale of 0 to 10, with 0 being no impairment and 10 being the worst impairment you can imagine, where would you place yourself?” Any answer other than zero means they recognize their own impairment. Most people will downplay their rating, but some will be forthcoming.

Another question you could ask is “Would you let your children ride on a bus if the bus driver was in your current condition?” This is kind of a loaded question, but you would be surprised how many people will say “no,” and it tends to personalize things for them.


It is crucial you document all your observations in your report. Remember, you are building a case based on the totality of the circumstances; the more circumstances or observations you have the better the case becomes.

It can take years of practice to be able to make and retain all your mental notes roadside and then put them into writing later. To help increase your proficiency with this, focus on committing to memory the things your video systems cannot or are unlikely to capture and fill in the rest by reviewing your video when writing your report if your agency's policy allows.

Think outside the box when interviewing violators and get creative. Use all the tools available to you during this phase of the investigation and take your time. If you have conducted a thorough personal contact, you will have a pretty good idea of whether the violator is impaired or intoxicated. Then you can move on to confirm your suspicions by administering SFSTs in the pre-arrest screening phase.

In the next article of the series, we will look at how officers can avoid field sobriety tests missteps. Click here.

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