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What is Probable Cause and Why is it Important?


The term probable cause comes from the Fourth Amendment to the U.S. Constitution, and refers to a requirement that police have a sufficient reason to conduct a search, seize property, or make an arrest. Since probable cause is a somewhat abstract idea, the amount of probable cause that officers need to conduct an arrest, search, or seizure can be subjective, and a judge has the final word on whether it exists in a given situation.

Probable Cause for an Arrest

Police officers must have an adequate reason to arrest someone, meaning that they must have some evidence that a person has committed, is committing, or is about to commit a crime. This evidence must include specific circumstances or facts, and cannot exclusively be based on a suspicion or hunch.

Detentions, however, including temporary vehicle or pedestrian stops, only require reasonable suspicion. This means that under the circumstances, a reasonable person would believe that criminal activity may be in play and that further investigation is justified.

While the amount of probable cause needed for an arrest is rather subjective, a judge must agree with the police officer in order for it to be valid.

Probable Cause for a Warrant

In order for a police officer to obtain a warrant, they must sign an affidavit explaining why they believe probable cause exists to either arrest someone or search their property. A judge will then review the affidavit and issue the warrant if they are in agreement with the officer.

In some cases, warrants are not required. These include when an officer witnesses a felony in a public place, pulls over a driver believed to be breaking a law, or when an officer searched property after a lawful arrest. If an arrest was made without a warrant, the officer must still show probable cause after the fact, and the defendant cannot be prosecuted until probable cause is established.

Probable Cause for Search and/or Seizure

Before an officer can search or seize someone’s property, they must have a legitimate reason to believe that the items in question are stolen, contraband, or evidence of a crime. Police must obtain a warrant before the search and seizure can take place. Any evidence obtained without a warrant cannot be used against the defendant in court because the search was illegal and subject to the “exclusionary rule.”

Facing Criminal Charges?

Are you being charged with a crime, but believe that your arresting officer acted on insufficient evidence? Police officers and municipalities can be sued for malicious prosecution or false arrest if they did not have probable cause to arrest you or search your property. Remember that suspicions alone are not enough to arrest you. Police officers have a duty to abide by our nation’s belief in protecting innocent people until they are proven guilty. For the aggressive representation you need to safeguard your rights, do not hesitate to contact the St. Louis criminal defense lawyers at the Hammer Law Firm, LLC for a free consultation.

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