What Is Probable Cause in Texas Law?

The Constitutional Standard for Arrest

Probable cause is the Fourth Amendment standard police must satisfy before arresting someone — enough specific, articulable facts to reasonably believe that a person has committed or is committing a crime. It is higher than reasonable suspicion (which justifies a stop) but lower than proof beyond a reasonable doubt (the criminal trial standard). An arrest without probable cause is an unlawful seizure under the Fourth Amendment, and evidence obtained during that arrest is suppressible under Texas Code of Criminal Procedure Art. 38.23.

How Officers Establish Probable Cause in DWI Cases

In a DWI context, officers build probable cause to arrest through their observations during the traffic stop: the odor of alcohol, bloodshot or watery eyes, slurred speech, flushed face, admission to drinking, and field sobriety test performance. Each element is individually challengeable — the officer’s subjective description of what they observed can be contradicted by dashcam video, SFST administration can be shown to deviate from protocol, and statements obtained without proper Miranda warnings may be inadmissible.

Probable Cause vs. Reasonable Suspicion

The two standards are often confused. Reasonable suspicion — the lower standard — is what justifies the initial stop. A speeding violation, a swerve, a taillight out. Probable cause — the higher standard — is what justifies the arrest. The officer must develop additional articulable facts during the stop that support a reasonable belief the driver is intoxicated. A stop can be valid under reasonable suspicion while the arrest that followed lacks probable cause.

Challenging Probable Cause in Travis County Courts

A motion to suppress based on lack of probable cause is filed in the Travis County Courts at Law (misdemeanor) or District Courts (felony) at the Blackwell-Thurman Criminal Justice Center. If the judge finds that probable cause was lacking, the arrest is unlawful and any evidence obtained incident to the arrest is suppressible. This challenge is independent of — and can be filed alongside — the challenge to the reasonableness of the initial stop. Learn more on our Austin criminal defense page.