What Are "Reasonable Suspicion" & "Probable Cause?"

You are constitutionally protected from “unreasonable” searches and seizures by law enforcement, but this concept becomes a lot cloudier when it comes to driving while under the influence of drugs or alcohol. Because law enforcement can’t just stop any random person and force them to consent to a search, police must follow a very strict set of procedures in order to legally establish a belief that a crime has been committed and then make an arrest in order to legally obtain any evidence. This is done using two principles: “reasonable suspicion” and “probable cause.” Let’s take a closer look at these concepts and learn how they impact your OWI case.

The OWI Arrest Process

Law enforcement can’t simply arrest someone just because they think there’s a possibility that they might be drunk. This is how mistakes are made, people are falsely arrested, and law enforcement agencies find themselves facing lawsuits from falsely-accused individuals. Therefore, the onus is on officers to make sure their arrests are being made after fully-confirming their suspicions that a crime has been committed.

In the case of OWI, this is done by establishing “probable cause,” which essentially just means that officers have witnessed enough evidence to support their theory, and they can justify making an arrest and searching someone who they suspect was driving while intoxicated. When you are arrested, you are required by law to submit to a blood or breath test, the results of which can be submitted to the court and used against you.

But in order to establish probable cause, an officer must first be alerted to the fact that a crime might be taking place. Again, this isn’t just done randomly, but must be done using a concept known as “reasonable suspicion.” Reasonable suspicion is like probable cause, only not quite at the level of knowing a crime has been committed.

Let’s look at an example. Say a police officer watches a bar patron leave, get behind the wheel, and then take off. That alone is not enough reason to make a stop: the officer does not know if the patron has been drinking. However, when the patron starts swerving in their lane, the officer can begin to suspect that the driver may in fact be intoxicated. While this isn’t enough to make an arrest (probable cause), it is enough for the officer to pull the driver over and continue their investigation. This is reasonable suspicion. At this point, the officer could then conduct field sobriety tests to further increase their suspicion until it turns into probable cause, allowing them to reasonably make the arrest.