How Police Officers Determine Probable Cause for DUI Arrests

Meaning and Its Importance

A probable cause exists when:

1. Certain facts and circumstances are available to a police officer when making an arrest.
2. These facts and information possessed by the police officer would cause a reasonably cautious person to assume that a crime has been committed.

It is unlawful for an officer to make a traffic stop or DUI arrest without probable cause. Additionally, any unlawfully obtained evidence may be inadmissible in court.

For example, driving under the influence (DUI) is considered a criminal offense with life-changing consequences. However, an illegal traffic stop serves as a defense against the prosecution’s evidence against you.

What Kind of Behaviors Give Rise to a Reasonable Suspicion?

An officer should not make a DUI arrest solely based on hunches. They must be able to show the facts that led to them having suspicions about the driver’s behavior. Generally, reasonable suspicion is a lower standard than probable cause.

Several behaviors may be used to establish reasonable suspicion, including:

• Drifting

• Driving erratically

• Driving in between lanes

• Driving too slowly

• Driving at high speed

• Driving without a headlight

• Driving without a license plate

• Driving through red lights

• Stopping a vehicle for no treason

• Swerving

• Weaving

What Behaviors Establish Probable Cause in DUI Investigations?

After making the traffic stop, the officers will search for signs of intoxication. The following behaviors can serve as evidence to establish probable cause:

• Bloodshot or watery eyes: Drinking large amounts of alcohol may cause redness in the eyes. Officers often cite bloodshot eyes as a sign of intoxication. However, other factors, such as allergies or crying, may lead to redness.
• The smell of alcohol on a motorist’s breath: Law enforcement officers usually pay attention to the driver’s breath. However, it is not a very reliable sign.
• Slurred speech: High levels of intoxication can lead to slurred speech. Other reasons for slurred speech may include a brain tumor, stroke, or migraine. An officer unfamiliar with their voice will be unaware of how they speak.
• Verbal admission of intoxication: Verbal admissions can damage the chances of avoiding a DUI conviction. It is important to speak to a lawyer before admitting to consuming alcohol.
• Failed field sobriety tests (FSTs): Failing field sobriety DUI testing, such as the one-leg stand or walk-and-turn, may show signs of intoxication. A skilled attorney can prove the inaccuracy of these tests by considering other factors.
• Failed breathalyzer test: Breathalyzer readings measure the driver’s blood alcohol level. Failed readings indicate that the driver is above the legal limit. However, these readings can be inaccurate due to faulty breath machines.

Some DUI arrests occur after a law enforcement officer discovers these signs at an accident scene. The prosecution may use such signs as evidence in court to prove that the driver was drunk driving.