Police officers have justification for a traffic stop or arrest. In DUI cases, the law requires law enforcement agents to prove reasonable suspicion for stopping a person in traffic and probable cause for arresting them for a DUI charge.

Your DUI attorney can challenge your DUI charge based on the standards of reasonable suspicion and probable cause by filing a motion to suppress evidence. Here is a look at what reasonable suspicion and probable cause entail.

What Is Reasonable Suspicion?

For a police officer to stop your vehicle and detain you for a DUI offense, they must establish reasonable suspicion. This means the officer should have sufficient reason, based on their training and experience, to believe that a crime has been committed or will be committed. Reasonable suspicion is subjective, which means it is different depending on the circumstances.

For example, if a police officer sees a driver committing a traffic violation like failing to signal while switching lanes or running a red light, there is reasonable suspicion that the driver may be intoxicated, and the officer can stop their vehicle.

What Is a Probable Cause? 

Probable cause needs to be established for a police officer to search your vehicle or arrest you for drunk driving. The officer should provide sufficient evidence a reasonable person would believe that a crime is or has been committed. Probable cause for DUI cases is established from the police officer's observations and breath-test results. 

For example, a police officer can pull over a vehicle. After interacting with the driver, the officer notices the driver's slurred speech, bloodshot eyes, or that the driver's breath stinks of alcohol. An officer can claim they had probable cause because of your physical features and that field sobriety test results confirmed their suspicions.

Challenging Reasonable Suspicion and Probable Cause

Your DUI attorney can file a motion to suppress evidence in a DUI case by challenging the basis of a police officer's reasonable suspicion and probable cause. For example, a police officer may claim they stopped your vehicle because you didn't signal when changing lanes. However, this law can be interpreted as applying to cases where another vehicle will be affected if you don't signal.

Another scenario is when the probable cause is based on weak observations. For example, a police officer may arrest you merely because your eyes are bloodshot and your breath smells like alcohol. However, your DUI attorney can claim that these are the effects of your medication. It's ideal to work with a DUI attorney to consider all your legal options.