Cynthia A. Stewart, P.A.
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Cynthia A. Stewart, P.A.

Mississippi Trial Lawyer

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An Experienced Focus On Your Legal Needs

What is reasonable suspicion for a drunk driving stop?

On Behalf of | Mar 11, 2024 | DUI

Reasonable suspicion is a critical concept in drunk driving traffic stops. It’s a legal standard that allows police to stop and briefly detain a driver if they have a reasonable belief, based on specific and articulable facts, that the driver is intoxicated.

Understanding how officers establish reasonable suspicion and proceed to determine probable cause for an arrest is essential for any driver.

Establishing reasonable suspicion

Reasonable suspicion for a drunk driving stop can arise from various observations. These might include erratic driving behavior such as swerving, speeding or braking irregularly. It can also come from traffic violations like running a stop sign.

Field sobriety tests

Once a driver is stopped, officers may conduct field sobriety tests if they suspect drunk driving. These tests assess a driver’s balance, coordination and ability to perform tasks requiring divided attention. Standardized field sobriety tests include:

  • The horizontal gaze nystagmus test
  • The walk-and-turn test
  • The one-leg stand test

Performance on these tests can provide further evidence of impairment. These tests are subjective and can be influenced by various factors, including the driver’s physical condition and nervousness.

Chemical tests for probable cause

To establish probable cause for an arrest, officers often rely on chemical tests, which provide more objective evidence of intoxication. These tests measure the alcohol content in a driver’s breath, blood or urine. The most common is the breathalyzer test, which measures the blood alcohol concentration (BAC) in a driver’s breath.

A BAC level at or above the legal limit, typically 0.08%, can provide probable cause for an arrest. Refusal to submit to these tests post-arrest can result in penalties because implied consent laws require drivers to comply with BAC testing.

The transition from reasonable suspicion to probable cause

The progression from reasonable suspicion to probable cause is critical to a drunk driving stop. Reasonable suspicion allows an officer to stop and detain a driver for further investigation, while the results of field sobriety and chemical tests can elevate the situation to probable cause, justifying an arrest.

Understanding the concepts of reasonable suspicion and probable cause is vital for drivers. For drivers, being aware of these standards can provide insight into the legal processes and their rights during a traffic stop for suspected drunk driving. Those who have already been arrested can benefit from seeking personalized legal guidance, however, as each case is ultimately unique.