Probable Cause and Arrest

Fourth Amendment to the Constitution of the United States
"The right of the people to be secure in their persons, houses, papers, and effects, against unreasonable searches and seizures, shall not be violated, and no Warrants shall issue, but upon probable cause, supported by Oath or affirmation, and particularly describing the place to be searched, and the persons or things to be seized."

Though the Fourth Amendment's language focuses on search warrants, the concept of probable cause comes into play in other interactions between citizens and law enforcement. One of the most important is when the police must decide whether probable cause exists to make an arrest.

Because law enforcement officials wield such great power - such as the authority to arrest and detain citizens - our legal system defines standards that have to be met before action can be taken. After an arrest is made, one of the oversight duties of the courts is to ask this question: Could a reasonable person deduce from the available evidence that a crime had been or was being committed?

The standard of probable cause is different than reasonable suspicion, which comes into play when police want to briefly detain and question people regarding a crime. Probable cause is a more demanding standard that requires more evidence and suspicion of wrongdoing. The best way to understand the difference between the two is by illustration.

Consider a theft from a liquor store. Police respond to the scene and question the store manager, who gives them a list of the items stolen. They also review surveillance video, which is black and white and grainy but shows a sedan speeding out of the parking lot. After they leave the store and drive around the surrounding neighborhood, they see a car that looks like it might be the one seen in the video, though they can't be certain. The standard for reasonable suspicion has been met to initiate a traffic stop and question the driver. However, if the driver has a plausible explanation for his recent whereabouts and if no other evidence exists linking him to the crime, the standard of probable cause has not been met to make an arrest.

For probable cause to exist, the police would need something like this scenario: In the course of questioning the driver, it is found that the car is registered to someone else. In addition, the driver becomes confused when attempting to explain his relationship to the registered owner. Finally, a bottle of alcohol that was on the list of items stolen from the liquor store is seen in the back seat of the car. The driver might insist that he has just pulled off the freeway and is on his way to a party at a friend's house, but the evidence most likely is sufficient to meet the standard of probable cause. The police can move from detention and questioning to arrest.

It's important to keep in mind that an arrest is the beginning, not the end, of the criminal justice process. Our system presumes defendants innocent until proven guilty. In the scenario above, the defendant might actually be innocent, though the initial evidence was sufficient to make an arrest. Criminal defense lawyers defend their clients by gathering and reviewing evidence, challenging illegal procedures, presenting their clients' version of events, and protecting their clients' rights and long-term interests.

If you have questions about probable cause, or any other criminal defense topic, call me at (916) 442-1200.