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What Is Probable Cause

Generally speaking, probable cause means that a reasonable person would believe that a crime has taken place. Probable cause is a requirement found in the Fourth Amendment and must be met before police can make an arrest or conduct a search or receive a warrant.  

guy being investigated by police

For example, recently in the University of Idaho murder case, the probable cause affidavit outlined what law enforcement used to arrest Bryan Kohlberger. It described the evidence gathered including DNA, cell phone usage, and camera sightings of Kohlberger’s white Honda Elantra. They showed a judge that a reasonable person would believe this man committed the 4 murders and the judge in turn issued the arrest warrant.


As a Fourth Amendment protection, it is incorporated into Tennessee Law. It serves to protect the public from unlawful or frivolous actions from law enforcement. Law enforcement must be very careful to comply with the probable cause statute if they want to make a search, an arrest, or a conviction.

For example, if a known drug dealer is simply walking down the street in the afternoon -No probable cause for any illegal activity. However if that known drug dealer is observed to be selling drugs, there may be probable cause to arrest or maybe at least search the suspect.

When Probable Cause May Be Applied

The factors involved in the application of probable cause vary depending on a given situation, even if law enforcement officials already possess a warrant for a search or arrest.

Probable cause usage has to vary because the term itself does not specifically state what actions or activities would qualify as probable cause. The vagueness exists because crime and those with criminal intent do not announce their intentions or communicate the time and place of a planned crime. While bank robberies in cartoons can be identified by people running away from banks with bags emblazoned with money symbols, the ability to identify actual criminals proves to be much more difficult. 

Before law enforcement officials can investigate or arrest a suspect, the Fourth Amendment of the United States Constitution requires them to have probable cause of a potential crime before allowing them to proceed. Generally speaking, the probable cause would be the total amount of information available to law enforcement officials that confirms the possibility of a crime.

For example, a detective cannot investigate or arrest a suspect for stealing cars on the basis of “they look guilty and mean.” The detective would have to establish probable cause by detailing the information suggesting a possible crime. For this example, the detective could share how the suspect was known to be in the area at the time the crime was committed, the suspect has a criminal record for automobile theft, and the criminal was seen at the bank the next day making a huge deposit of funds.

Likewise, law enforcement officials tasked with maintaining road safety cannot pull over and arrest every driver on the road. Instead, they have to monitor the roadways for drivers showcasing signs of driving under the influence, speeding, or driving in a reckless and endangering manner. Those all constitute a probable cause of a moving violation, which allows law enforcement to focus on the specific problems while ensuring every other driver obeying the rules of the road does not get cited without cause.

Contact Us Today

If you have been arrested, you need a good criminal defense attorney. David Clarke has been defending his clients with compassion and care. He understands that his experience and expertise can be used for your defense. Please contact The Clarke Law Firm today.