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Probable Cause

"Probable cause" is the legal basis that allows police to arrest someone, conduct a search, or seize property. This requirement comes from the Fourth Amendment of the U.S. Constitution, which states that:

"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 searched."

So, at a minimum, in order for a court to issue a warrant, it must be supported by a showing of probable cause. This article will provide a definition of probable cause and examine the probable cause standard in connection with detention, arrest, search, seizure, and prosecution.

Warrants and Probable Cause

To get a warrant, an officer will sign an affidavit stating the facts that they know from their own observation, or from the observations of citizens or police informants. These facts support their claim that probable cause exists to conduct a search, seize property, or make an arrest.

If a judge or magistrate agrees that probable cause exists based on a "totality of the circumstances," they will issue an arrest warrant or search warrant. The judge is relying upon the honesty of the police officer in presenting accurate information. The accused is not present to rebut the claims.

There are instances where warrants are not required to arrest or search, such as arrests for crimes that were personally witnessed by an officer. If a warrantless arrest does occur, it may be subject to legal challenge by the defense in a subsequent proceeding.

Temporary Detention Does Not Require Probable Cause

Some examples of temporary detention are traffic stops, questioning of pedestrians, or the detention of building occupants while officers execute a search warrant. Temporary detention requires only "reasonable suspicion," not probable cause.

If the police have "reasonable suspicion," it means they are acting on specific facts and inferences regarding a specific person. "Reasonable suspicion" uses the "reasonable person standard." Would a reasonable person believe criminal activity was at hand and further investigation was required?

Detention can become a formal arrest if the detaining officer develops probable cause to charge crime as a result of the investigation. For the detainee, the line between detention and arrest is not always clear.

Probable Cause for Arrest

If, during an investigation, a police officer announces that a person is under arrest and places them in physical restraints, that is clearly an arrest. At that moment, the arresting officer must have probable cause to believe the person committed a specific crime.

Probable cause for arrest exists when facts and circumstances known by the police officer would lead a reasonable person to believe that the suspect has committed, is committing, or is attempting to commit a crime.

The amount of evidence required to show probable cause is less than "a preponderance of the evidence," which is the standard used to prove facts in court. However, probable cause requires more than "a reasonable suspicion." Probable cause must be based on objective facts; it cannot be based upon a hunch.

Someone arrested or charged without probable cause could file a civil lawsuit for false arrest or malicious prosecution. This type of suit will not succeed, however, if the arresting officer was simply mistaken.

Probable Cause to Search Person or Property

Probable cause to search exists when facts and circumstances known to the law enforcement officer provide the basis for a reasonable person to believe that a crime was committed at the place to be searched, or that evidence of a crime exists at the location.

The police officer can then seek a search warrant from a judge or magistrate. A search warrant gives the officer permission to conduct a limited search. Search warrants specify the place to be searched, as well as items to be seized.

When a Search Warrant Is Not Needed

There are circumstances when a search warrant is not required, such as:

  • When the police have consent from a person who has use or control of the premises
  • When conducting a search connected to a lawful arrest
  • In an emergency situation that threatens public safety (a building fire) or the potential loss of evidence
  • If a car has been impounded and an inventory is being taken as part of standard procedure
  • If contraband is "in plain sight" from a location where the officer has a right to be present (outside the car door, at the front door of a house or apartment)

Probable Cause To Seize Property

Probable cause to seize property exists when facts and circumstances known to the officer would lead a reasonable person to believe that the item is contraband, is stolen, or constitutes evidence of a crime.

When a search warrant is in effect, police generally search only for the items described in the warrant. However, any contraband or evidence of other crimes they come across may, for the most part, be seized as well.

If evidence was gathered as a result of an illegal search, it could be suppressed in court. That means it would not be allowed to be presented to the jury by the prosecution at trial. At a suppression hearing, the judge decides whether the "exclusionary rule" applies to a particular piece of evidence after hearing testimony from the prosecuting and defense attorneys.

Probable Cause for Criminal Charges

The concept of probable cause extends to the prosecution of a criminal case. Under the Federal Rules of Criminal Procedure, a prosecutor must believe that there is probable cause that the person actually committed the crime before they recommend further investigation or prosecution.

Get Legal Help With Your Probable Cause Questions

The Fourth Amendment protection against unreasonable search and seizure depends on the finding of probable cause. It is one of the most important legal protections people have against law enforcement overreach in the criminal law system.

If you believe you were subjected to unlawful search and seizure, talk to an experienced criminal defense lawyer near you.

You Don’t Have To Solve This on Your Own – Get a Lawyer’s Help

Meeting with a lawyer can help you understand your options and how to best protect your rights. Visit our attorney directory to find a lawyer near you who can help.

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