The first real storm of the season along the Wasatch Front changes everything about a DUI stop. Cars slide through intersections on Harrison Boulevard, drivers hug the lane line on I-15 because the paint has disappeared under slush, headlights are forgotten in the 5 p.m. dark, plates and taillights are caked with road spray, and fender-benders tie up Riverdale Road. Each one of those is a reason for an officer to make contact. And once contact is made, the roadside investigation that follows takes place in exactly the conditions the standardized field sobriety tests were never designed for.
This article is about the intersection of winter and DUI law in Utah: why there are more stops, how cold and snow undermine the tests officers rely on, what the training manual actually says, and what to do if you are standing on a frozen shoulder with a flashlight in your eyes.
Winter gives officers more reasons to stop you
A DUI case starts with a traffic stop, and a traffic stop requires reasonable suspicion of some violation. In July that means speeding, a rolling stop, a lane change without a signal. In December the list grows:
- Lights. Utah Code § 41-6a-1603 requires headlights from sunset to sunrise and whenever conditions limit visibility. Sunset in Ogden is before 5:15 p.m. through December, and the number of drivers running on daytime running lights alone, with no taillights, is enormous.
- Obscured plates and lenses. Snow and road grime covering a license plate or a brake light is an equipment violation and one of the most common pretexts for a winter stop.
- Lane position. Utah’s lane statute, § 41-6a-710, requires a driver to stay in a single lane “as nearly as practical.” On a road where the lines are under two inches of slush, what is practical is a real question, and a single drift is thin evidence of anything.
- Speed for conditions. Utah’s basic speed rule allows a citation for driving too fast for conditions even under the posted limit, which gives officers wide discretion in a storm.
- Crashes. A slide-off or a low-speed collision brings an officer to your window with no stop required, and a DUI investigation can begin from any crash scene.
The stop itself is usually lawful. The defense question is whether the officer had grounds to turn a lights-out stop into a DUI investigation. Nervousness, cold-reddened eyes, and a slow response at the window in a snowstorm are not indicators of impairment, and a stop that was extended without specific signs of impairment can be challenged in a suppression motion.
What the training manual says about surface and conditions
Every Utah officer who administers field sobriety tests was trained from the NHTSA DWI Detection and Standardized Field Sobriety Testing curriculum. That manual is explicit: the walk-and-turn and one-leg stand are to be administered on a reasonably dry, hard, level, non-slippery surface. If such a surface is not available, the manual tells officers to move the subject to a suitable location or to administer only the horizontal gaze nystagmus eye test. The manual also acknowledges that the tests were validated under ideal conditions and that field conditions often are not ideal — which is why the training requires officers to document departures.
Consider what a December stop looks like against that standard. The shoulder of I-15 or US-89 is crowned, so it slopes toward the barrier. It is covered in slush, sand, and salt. The temperature is in the twenties. Wind off the Great Salt Lake is pushing snow sideways. Passing trucks throw spray and light. The driver is wearing winter boots or dress shoes with no tread, a heavy coat that changes balance, and has been sitting in a cold car for ten minutes with adrenaline running. The officer’s instructions compete with traffic noise. Then the driver is asked to stand on one foot for thirty seconds and walk nine heel-to-toe steps on an imaginary line.
The studies that produced the walk-and-turn and one-leg stand were conducted indoors in the late 1970s and early 1980s by the Southern California Research Institute, under NHTSA contract, with sober and dosed volunteers on level floors. Even in those conditions the tests misclassified a meaningful share of sober subjects. Nothing in that research tells a jury what a 48-year-old in boots on a frozen crowned shoulder in a windstorm should be able to do. Our field sobriety tests page covers the three tests and the clues officers score; the winter point is that the clues are only meaningful when the conditions match the training.
The questions the officer is supposed to ask
Before the balance tests, officers are trained to ask about physical conditions that affect performance: injuries to the back, legs, or feet; inner-ear problems; age over 65; being significantly overweight; and footwear, including heels over two inches, which the manual says the subject may remove. In winter the footwear question cuts both ways — nobody should be asked to remove boots on ice, and nobody should be scored for stumbling in them. Whether the officer asked these questions, and what the body camera shows about the answers, is often the first thing we look at in a winter DUI file.
The eye test in the dark and the lights
Officers who skip the balance tests in bad weather lean on horizontal gaze nystagmus, the eye test. HGN is sensitive to its own conditions. The manual instructs officers to face the subject away from flashing emergency lights and passing traffic because those visual stimuli can produce nystagmus that has nothing to do with alcohol. A roadside at night in December, with light bars strobing off wet pavement and headlights sweeping past every few seconds, is the environment the manual warns about. Cold wind also makes eyes water, which interferes with the officer’s ability to observe the smooth pursuit and end-point clues. These are not technicalities; they go to whether the test result means anything.
The sleeping-it-off case
Winter produces a DUI case that summer rarely does: the person who decided not to drive, got into the car to stay warm, started the engine for the heater, and was found asleep in the driver’s seat. Utah’s statute covers “actual physical control,” and courts weigh where you were sitting, whether the engine was running, where the keys were, and whether the car was legally parked. If you are going to wait out a cold night in a car, the back seat with the keys out of reach is a different legal situation from the driver’s seat with the engine on. Our page on DUI in a parked car explains the factors courts use.
Ski season on the canyon roads
From the first Snowbasin opening weekend through spring, SR-39 through Ogden Canyon, SR-167 over Trappers Loop, and the road down from Powder Mountain carry a steady stream of skiers who stopped for a drink in the lodge or in Huntsville. Weber County deputies and UHP know the pattern and patrol accordingly. Mountain roads add their own stop reasons — speed on curves, lane position, chains and traction issues — and their own test-condition problems: there is no level, dry surface on a canyon pullout in January. The same analysis applies, and the stakes are the same.
If you are stopped in a storm
- Pull over safely, well off the travel lane, and turn on your hazards. Keep your hands visible.
- Provide license, registration, and insurance. You do not have to answer where you are coming from or whether you have been drinking.
- If asked to step out, you may decline field sobriety tests. Say it politely: “I don’t want to do any tests.” Do not argue about the weather; let your lawyer make that argument.
- Understand that the chemical test after arrest is governed by implied consent, with license consequences for refusal.
- Afterward, note the exact location, the surface, the weather, your footwear, and what you were asked. Photograph the spot in daylight if you can.
- Request your Driver License Division hearing within 10 days, and call our office. Staff answer 24 hours a day and an attorney reviews every case assessment.
Weather records from the National Weather Service, UDOT road-condition logs, and the officer’s own dashboard and body camera footage are all obtainable. In a winter DUI case they are frequently the most important evidence in the file.