You’re driving home late on a Friday night. You had two drinks at dinner three hours ago. Blue lights flash in your rearview mirror. In the next fifteen minutes, an officer is going to build — or fail to build — a case against you. Understanding exactly how that happens is the single most useful thing you can know if you ever face a DWI charge in Houston.
Herman Martinez spent years as a Harris County chief prosecutor. He watched officers testify. He read thousands of DWI reports. He knows the investigation sequence from the inside. Now he uses that knowledge to defend people on the other side of that equation. What follows is a detailed breakdown of exactly what Houston officers are trained to observe, document, and testify about — and where their cases often fall apart.
The DWI Investigation Starts Before You’re Pulled Over
Most people think the DWI investigation begins the moment the officer’s lights come on. It doesn’t. It begins with your driving pattern — and in Harris County, that observation is frequently caught on dashcam before you ever know you’re being watched.
The National Highway Traffic Safety Administration (NHTSA) trains officers to use 24 driving cues as indicators of possible impairment. These are listed in the NHTSA DWI Detection and Standardized Field Sobriety Testing manual, which is the bible of every DWI investigation in Texas. Officers are taught that certain behaviors have statistically significant correlations with blood alcohol levels above .08.
The 24 NHTSA Driving Cues: What Officers Watch For
The cues fall into several categories. Problems with maintaining proper lane position: weaving, drifting, straddling a lane line, swerving, or turning with a wide radius. Speed and braking problems: stopping too far ahead of or behind a line, accelerating or decelerating erratically, varying speed inappropriately. Judgment problems: following too closely, improper lane changes, failing to signal, driving in the wrong lane or the wrong way. Vigilance problems: driving without headlights, failing to respond to traffic signals, slow response to signals, or stopping in the roadway for no reason.
Here’s what matters to your defense: the officer is going to document whatever driving pattern prompted the stop. But dashcam footage tells the real story. In many cases, the reported driving conduct is far more dramatic in the police report than what the video actually shows. A “weave” that spans a few inches becomes a “swerving across multiple lanes” on paper. Herman reviews every second of dashcam footage to compare what the officer wrote against what actually happened.
The Traffic Stop: Phase Two Begins
Once the officer activates lights and you pull over, Phase Two of the NHTSA protocol begins: personal contact. Officers are trained to observe your stopping behavior — did you stop abruptly? Did you pull too far past the intended location? Did you drive a long distance before pulling over? All of these go into the report.
As the officer approaches your vehicle, the observation continues. They’re watching through the window before you even roll it down. They note: Is the driver reaching for something? Fumbling? Looking nervous? Are there containers visible in the car?
When you roll down the window, the checklist accelerates rapidly.
The Approach: Everything the Officer Notes at Your Window
Officers are trained to conduct what amounts to a systematic assessment during those first 30 seconds at your window. Here is what they’re noting and what they write about it:
Odor of alcohol. This is the most commonly cited observation in Houston DWI reports. “I detected a strong odor of an alcoholic beverage emanating from the vehicle/from the driver’s breath.” What the officer is trained to know: alcohol itself is odorless. What they actually smell is the denatured impurities in alcoholic beverages. A one-drink driver and a six-drink driver can smell the same. The smell doesn’t tell you how much someone drank — it only confirms they consumed something at some point. Herman challenges this observation constantly because it’s unreliable as a measure of impairment.
Bloodshot/watery eyes. “Driver’s eyes were red and watery.” What the officer is trained to note but rarely records: it was late at night, the driver was tired, they had allergies, they wear contact lenses, or they’d been driving with the window down. Eye redness is correlated with about 80 different conditions that have nothing to do with alcohol. The officer writes it down. It looks bad in a report. It rarely survives cross-examination by an experienced attorney.
Slurred or thick speech. Officers often write “driver’s speech was slurred” or “driver had thick, slow speech.” This is highly subjective. Accents, dialects, speech impediments, anxiety, medical conditions — all of these produce speech that an officer unfamiliar with you might characterize as slurred. And here’s the key question Herman always asks at trial: What is your baseline for this person’s normal speech? You just met them. You have no baseline. You’re guessing.
Fumbling with license and registration. “Driver had difficulty locating and providing documents.” Fumbling with your wallet in the dark, with an officer’s flashlight in your eyes, while your heart is pounding — that’s not impairment. That’s a completely normal human response to a stressful situation. Officers are trained to note it. Juries often recognize it for what it is when a skilled attorney points it out.
Admission of drinking. “Driver stated he had consumed two beers earlier in the evening.” This one is significant. Any admission of alcohol consumption gets written down and will be used against you. It is not helpful to say you only had “a couple” or “just a few.” Anything you say becomes part of the record. You have the constitutional right to remain silent, and that right applies during a traffic stop after the officer has asked investigative questions about your alcohol consumption.
Exit from Vehicle: Phase Three
If the officer suspects impairment, they’ll ask you to step out of the vehicle. They’re trained to watch how you exit. Do you use the door to steady yourself? Do you stumble? Do you grab the car? These observations go in the report.
They’ll also observe your clothing, whether you sway while standing, and how you follow instructions. All of this becomes part of the narrative that builds toward field sobriety tests.
Field Sobriety Tests: The Choreography of Probable Cause
The three standardized field sobriety tests — the Horizontal Gaze Nystagmus (HGN), the Walk and Turn, and the One Leg Stand — are the centerpiece of most DWI investigations. Officers in Texas are trained by NHTSA on exactly how to administer these tests and exactly what to look for. Understanding the scoring criteria is essential to understanding how a DWI case is built. For a deep dive on how field sobriety tests work and their significant limitations, we’ve covered that thoroughly elsewhere.
What matters here is this: these tests have rigid administration protocols. If an officer doesn’t follow the exact protocol — if they give instructions wrong, if they demonstrate incorrectly, if the surface isn’t reasonably dry and level, if there’s traffic affecting the subject — the results are legally compromised. Herman watches every available video of field sobriety tests looking for protocol deviations.
Common Police Report Phrases — and What They Actually Mean
After years of reviewing DWI reports for both the prosecution and the defense, Herman has identified a glossary of stock phrases that appear in report after report. Here’s a translation guide:
| What the Report Says | What It Actually Means | Defense Challenge |
|---|---|---|
| “Strong odor of alcoholic beverage” | Driver consumed alcohol at some point — quantity unknown | Odor doesn’t measure BAC or impairment level |
| “Bloodshot, watery eyes” | Eyes were red — cause unknown | 80+ non-alcohol causes; no medical baseline |
| “Slurred, thick speech” | Speech sounded unusual to this officer | No baseline; natural accent/dialect/anxiety |
| “Unsteady on feet” | Subject didn’t stand perfectly still | Uneven surface, medical conditions, footwear |
| “Unable to follow instructions” | Subject didn’t perform tests to officer’s satisfaction | Instructions may have been given incorrectly |
| “Performed poorly on SFST” | Officer observed clues per their subjective count | Non-standardized administration, medical factors |
| “Admitted to consuming alcohol” | Subject made a statement about drinking | Amount admitted rarely matches alleged impairment |
| “Based on my training and experience” | Opinion statement, not objective fact | Can be challenged as subjective; experience questioned |
What Dashcam Shows vs. What the Report Says
Texas law enforcement agencies in major urban areas like Houston increasingly deploy in-car dashcam and officer body cam systems. This is enormously significant for DWI defense — and it cuts both ways.
Sometimes the video confirms what the officer wrote. The driver really was swerving badly. The field sobriety tests really were a disaster. In those cases, Herman gives clients an honest assessment of what the evidence shows.
But far more often — particularly in marginal cases where a jury might have reasonable doubt — the video tells a different story than the report. The “weaving” was minor lane movement within the lane. The driver exited the car without stumbling. The speech on video sounds completely normal. The field sobriety tests, when you watch them critically, show an officer who gave ambiguous instructions and then counted clues anyway.
Herman requests every available piece of video evidence as early as possible. In Harris County, this means dashcam from the patrol car, body cam footage from the arresting officer and any backup officers, and booking facility video. Each camera captures different moments of the encounter and often catches things that never made it into the written report — including evidence that helps the defense.
When There Is No Video
Not every Houston-area agency has functioning cameras on every patrol car. When there’s no video, the case becomes a credibility contest between what the officer wrote and what the client experienced. Herman’s cross-examination strategy in no-video cases focuses on the officer’s inability to confirm their observations with objective evidence, the inherent subjectivity of the reported cues, and inconsistencies between the officer’s testimony and what a trained observer would expect to see if impairment was as obvious as claimed.
The Arrest Decision: Probable Cause Standard
Under Texas law and the Fourth Amendment, an officer must have probable cause — a reasonable belief based on articulable facts — to arrest you for DWI. That’s a legal standard, not just a gut feeling. Officers are trained to document enough facts to establish probable cause, which is why DWI reports tend to be dense with observations.
What many people don’t realize is that probable cause for arrest is a lower standard than proof beyond a reasonable doubt at trial. An officer can have enough to arrest you without having nearly enough to convict you. Herman’s job begins the moment of arrest — building the record that will eventually demonstrate why the evidence doesn’t rise to the level of proof beyond a reasonable doubt.
How Herman Martinez Reviews a DWI Police Report
When Herman takes a DWI case, the first thing he does is obtain the complete offense report, supplemental reports, and all available video. Then he goes through the report systematically, line by line, asking a specific set of questions:
Does the stated reason for the initial stop hold up? Is there a legal basis for the stop — a traffic violation, a specific NHTSA driving cue, equipment issue? If the stop itself was unlawful, everything that follows can be suppressed.
Are the observations physically consistent with each other? If the driver was severely impaired, the observed behavior should be consistent across all stages of the stop. A report that claims severe impairment but describes a driver who communicated clearly, exited the vehicle without assistance, and had a BAC of .09 — that’s an inconsistency worth exploring.
Were the field sobriety tests administered properly? Herman cross-references the officer’s description of the tests against the NHTSA administration protocols. Even small deviations matter — they call into question whether the test results are valid indicators of impairment.
What does the video actually show? This is often the most important question. Herman watches video with the report in hand, noting every discrepancy between written description and visual reality.
Are there any inconsistencies between the officer’s report and their testimony at the ALR hearing? If the officer already testified at an ALR hearing about the same stop, any inconsistency between that testimony and what they say at trial is impeachment gold.
Understanding how officers build DWI cases from the inside gives Herman a structural advantage in taking them apart. If you’ve been arrested for DWI in Houston or Harris County, you need an attorney who reads police reports the same way the officer wrote them — and then finds every place the story doesn’t hold together.
What You Should Do If You’re Pulled Over
While the purpose of this post is to explain the investigation sequence rather than provide real-time advice, a few practical points deserve mention. You are required to provide your license, insurance, and registration. You are not required to answer questions about where you’ve been, whether you’ve been drinking, or how much you’ve had. You can politely decline field sobriety tests in Texas — they are not mandatory. You will likely be arrested if you decline, but an arrest without field sobriety test evidence is often a weaker case. These are strategic decisions that require talking to an attorney, ideally in advance.
Ready to Talk to Someone Who’s Seen Both Sides?
If you’ve been arrested for DWI in Houston, the police report is just the beginning of the story — not the end of it. Herman Martinez has spent his career on both sides of these reports. He knows exactly what officers are trained to write, what juries are trained to hear, and where the gaps are between what’s on paper and what actually happened.
Call Herman at (713) 242-1779 for a free, confidential case evaluation. Or start with our free online case evaluation to get a preliminary assessment of your situation. The DWI investigation starts at the traffic stop. Your defense starts the moment you hire the right attorney.
