What drunk driving looks like from another vehicle

A drunk driver usually shows a pattern of erratic movement rather than a single mistake. Watch for a car that weaves between lanes without signaling, drifts toward the shoulder and corrects suddenly, or straddles the center line. The driver may brake hard for no reason, accelerate without warning, or maintain an inconsistent speed—speeding up and slowing down repeatedly over a short distance.

The most common sign is weaving. A sober driver who drifts once might be reaching for their phone or adjusting the radio. A drunk driver typically drifts multiple times in a short stretch of road, often crossing the center line or edge line. If you see a car cross the center line more than once in a few blocks, that's a strong indicator something is wrong with the driver.

Other movement patterns that stand out: turning too wide, taking corners too fast or too slow, or failing to maintain a consistent lane position. Some drunk drivers drive too slowly—well below the speed limit—because they're overcompensating and trying to be careful. Others drive recklessly fast. Both extremes, especially when paired with weaving, suggest impairment.

Key Takeaways

  • Weaving between lanes, drifting toward the shoulder, and straddling the center line are the most common signs of impaired driving.
  • Inconsistent speed—speeding up and slowing down repeatedly—combined with erratic steering is a strong indicator of intoxication.
  • Drunk drivers often brake suddenly without reason, turn too wide, or fail to use turn signals before changing lanes or turning.
  • If you observe these patterns over several blocks or minutes, not just a single mistake, contact local law enforcement with the vehicle's location and direction of travel.

Braking and acceleration patterns that signal impairment

Impaired drivers often brake at odd moments—stopping hard at a green light, braking on a straightaway with no traffic ahead, or tapping the brakes repeatedly for no apparent reason. This happens because their reaction time is delayed and their judgment is compromised. They may see a hazard late and overcorrect, or they may be confused about what they're seeing.

Acceleration is equally telling. A drunk driver might gun the engine suddenly, then ease off, then accelerate again—a jerky, unpredictable pattern. They may struggle to maintain steady pressure on the gas pedal. On a highway, this shows up as the car speeding up to 70 mph, then dropping to 50 mph, then back to 65 mph, all without traffic or road conditions changing.

Stopping at traffic lights is another moment to watch. A sober driver stops smoothly and waits. A drunk driver may roll through a red light, stop well short of the line, or stop in the wrong lane. They may also take an unusually long time to react when the light turns green—sitting through the first few seconds while other cars move.

Turn signals, lane changes, and navigation mistakes

Drunk drivers frequently fail to signal before turning or changing lanes, or they signal after they've already started moving. This happens because their attention is divided and their motor control is impaired. They may also signal in the wrong direction—turning left while the right signal blinks.

Watch for wide turns, especially at intersections. A sober driver turns within their lane. A drunk driver often swings wide, crossing into the adjacent lane or nearly hitting the curb. They may also turn from the wrong lane—making a left turn from the right lane, for example.

Navigation errors are common too. A drunk driver may miss their exit, realize it too late, and brake hard or swerve to correct. They may drive in the wrong direction on a one-way street, or turn onto a road and when ready turn back off. These aren't the mistakes of someone distracted by a phone—they're the mistakes of someone whose judgment and spatial awareness are compromised.

Headlight and windshield wiper use that seems off

Impaired drivers often forget to turn on their headlights at dusk or in low visibility, or they leave them on during the day. They may also forget to turn off their headlights after parking, which you might notice if you see a parked car with lights still running. This happens because the driver's attention is fragmented and they're not processing their environment normally.

Windshield wipers are another tell. A drunk driver may turn them on when it's not raining, or leave them off during rain. They may turn them on and off repeatedly without reason. These small details matter because they show the driver isn't fully aware of their surroundings or their vehicle's controls.

Headlight flashing—using high beams inappropriately or flashing them at other drivers—can also indicate impairment. A sober driver uses high beams deliberately. A drunk driver may flash them without reason or forget to switch back to low beams when approaching oncoming traffic.

How to respond if you suspect a drunk driver

If you observe these signs, do not try to stop the driver or engage with them. Instead, pull over to a safe location and call your local police non-emergency line or 911 if the driver is actively endangering others. Provide the dispatcher with the vehicle's license plate number, color, make, and model, plus the direction it was heading and the road it was on.

Stay on the line and describe what you observed: the weaving, the sudden braking, the failed signals. The more specific you are, the better. Tell the dispatcher where you last saw the vehicle and which direction it was traveling. If you can safely follow the car at a distance without putting yourself at risk, do so and continue to report its location, but do not attempt to pull it over.

If the driver is parked and you suspect they've been drinking, you can report the vehicle's location to police. If you witness a crash involving a driver who shows signs of impairment, call 911 when ready and remain at the scene if it's safe to do so. Your account of the driver's behavior before the crash can be important to law enforcement.

Signs visible when you're stopped next to the driver

If you pull up next to a suspected drunk driver at a red light or in traffic, you may notice additional signs. Look at the driver's head position—they may be leaning heavily on the steering wheel, nodding off, or looking confused. Their eyes may be unfocused or they may be staring straight ahead without blinking.

You might also notice the driver is eating, smoking, or holding a drink while driving. While these aren't proof of intoxication, they suggest divided attention. A drunk driver may also appear to be arguing with a passenger, or they may be alone but talking to themselves or the windshield.

Do not roll down your window or try to communicate with the driver. straightforward note what you see and report it to police if the driving behavior warrants it. Your safety comes first.

When to call police versus when to stay alert

A single weaving motion or one missed signal is not enough to report. Drivers make small mistakes constantly—reaching for a phone, adjusting the radio, or momentarily losing focus. The key is pattern. If you see multiple signs over several minutes or blocks, that's when you should call.

Call police if you observe: repeated weaving over a distance of at least a quarter mile, multiple sudden braking events with no traffic ahead, failure to use turn signals on multiple lane changes, or a combination of these behaviors. Also call if the driver is driving significantly slower or faster than traffic, or if they nearly hit another vehicle or object.

If you're unsure, it's better to report and let police investigate than to stay silent. Police receive many reports of suspected impaired driving, and dispatchers are trained to determine whether the behavior warrants a response. Your report might prevent a crash.

Frequently Asked Questions

What's the difference between a drunk driver and a distracted driver?

A distracted driver (texting, eating, adjusting the radio) usually makes brief, isolated mistakes and corrects quickly. A drunk driver shows a sustained pattern of erratic behavior—weaving repeatedly, inconsistent speed, and poor judgment over minutes. Distracted mistakes are usually forward-facing; drunk driving affects all aspects of vehicle control.

Can a driver be impaired but still drive in a straight line?

Yes. Some impaired drivers overcompensate and drive very carefully, staying in their lane but moving too slowly or braking unexpectedly. Impairment affects judgment and reaction time even when steering appears steady. Watch for the full picture: slow speed combined with sudden braking, or careful steering paired with missed signals.

Should I try to get the license plate number?

Only if you can do so safely without taking your eyes off the road for more than a glance. Your primary job is to drive safely and report the vehicle's location and direction to police. The dispatcher can relay this information to officers who may be in the area. Do not speed up to get closer to the vehicle or take risks to photograph it.

What if the driver is parked but I think they've been drinking?

If a parked car's engine is running and the driver appears impaired, call the non-emergency police line and report the vehicle's location and description. Police can check on the driver. If the car is parked and the driver is not in it, there's no when ready danger, so reporting is optional unless you believe they're about to drive.

Can I report a drunk driver if I didn't see them actually driving badly?

You can report what you observed—a driver who appeared impaired or was driving erratically—but police need specific details about the driving behavior, not just your suspicion. Describe what you saw: weaving, sudden braking, missed signals, or slow speed. The more specific you are, the more useful your report is.