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Suspected drunk driving stops: The basics

On Behalf of | Jun 14, 2024 | DUI

One of the most disheartening things a person can see when they’re driving is the flashing lights of a police vehicle behind them. Yet, police officers can’t (lawfully) conduct a traffic stop without having a valid reason, one of which might be the suspicion of drunk driving, so these lights generally mean that something significant is suspected to be going on.

Anyone who’s pulled over for a suspicion of drunk driving should know a few things about these stops. Each of these concerns can potentially influence their defense strategy if they’re arrested.

Reasonable suspicion for the stop

Reasonable suspicion is the legal standard that requires officers to have specific points that suggest a driver may be impaired. This is a much lower standard than probable cause.

Common indicators include erratic driving behaviors such as swerving, abrupt lane changes, excessive speeding or driving significantly below the speed limit. Other signs might include ignoring traffic signals, failing to use headlights at night or other unusual driving patterns.

If an officer observes such behavior, they are legally justified in stopping the vehicle to investigate further. The key aspect of reasonable suspicion is that it must be based on observable facts and not just a hunch.

Field sobriety tests to determine impairment

Once a driver is stopped, officers typically use field sobriety tests to assess impairment. These tests are designed to evaluate a driver’s physical and cognitive functions, which are often compromised by alcohol consumption.

Standardized field sobriety tests include the horizontal gaze nystagmus, one-leg stand and walk-and-turn. Performance on these tests provides officers with evidence of impairment, which can justify further testing or an arrest.

Chemical tests to determine blood alcohol concentration

Chemical tests, such as breath, blood or urine tests, are used to measure a driver’s blood alcohol concentration (BAC) accurately. The most common is the breathalyzer test, which estimates BAC by measuring alcohol levels in the breath. Blood tests are more accurate but require a medical professional to draw the sample. Urine tests are less common and generally used when other methods aren’t available.

Anyone who’s arrested for drunk driving should begin to prepare a defense strategy immediately. This may involve showing that there’s reasonable doubt about the way that impairment was determined. Seeking legal assistance is often beneficial in these cases given the complexities at issue and how much is at stake.