Probable cause is the weight of evidence that law enforcement officials need to obtain an arrest warrant or to perform a search and seizure of evidence. Although the concept of probable cause originates in federal law, it applies to both state and federal cases. “Lack of probable cause” is a common defense in criminal cases, and it has resulted in a multitude of acquittals. Ultimately, probable cause protects you against the arbitrary exercise of state power.
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The Definition of Probable Cause
A police officer has probable cause if their evidence would lead a “reasonable person” to believe that:
- A crime is, has been, or is about to be committed by a particular person (probable cause for an arrest); or
- A particular location holds evidence of a crime (probable cause for a search and seizure).
Evidence must generate probable cause based on a consideration of the “totality of the circumstances.”
The Constitutional Basis for Probably Cause
The Fourth Amendment to the US Constitution is part of the Bill of Rights that prohibits “unreasonable search and seizure.” The Fourth Amendment prevents law enforcement authorities from searching your home, your vehicle, or your person without justification. It also prevents the police from seizing your property as evidence without justification. It prevents the police from arbitrarily arresting you since an arrest is a seizure of a person.
Probable Cause for Arrest
There are two ways that probable cause can lead to an arrest:
- Probable cause to issue an arrest warrant. The officer will present evidence to a magistrate, who will issue an arrest warrant if they are convinced that the evidence establishes probable cause.
- Probable cause for an immediate arrest. Under certain circumstances, a police officer has probable cause to arrest someone without first obtaining an arrest warrant. The officer must witness the commission of the crime or witness evidence that the suspect has committed a crime (a defendant running out the back door of a commercial establishment after the officer heard shots fired, for example).
Sometimes a search initially conducted without probable cause for an actual arrest will uncover evidence that generates probable cause for an immediate arrest of the suspect.
“Probable Cause” vs. “Reasonable Suspicion”
“Reasonable suspicion” is enough evidence to justify pulling over a driver on the highway or performing a “stop and frisk” search of a person’s outer clothing on the street. It is not enough to justify either a search or an arrest, as probable cause is. It is easier for an officer to prove that they had reasonable suspicion than to prove that they had probable cause.
If you are driving erratically, for example, an officer may have reasonable suspicion to pull you over for a suspected DUI. The purpose of making you perform field sobriety tests (walking in a straight line, etc.) is to give the officer probable cause to arrest you. A positive breathalyzer test administered after the arrest might be enough to convict you.
Probable Cause for Search and Seizure
An arrest or a search must be “reasonable” to be legal, and probable cause defines what is reasonable. If you have probable cause, your search is reasonable, but if you lack probable cause, it is unreasonable.
Exceptions to the Probable Cause Requirement in Search and Seizure Cases
The police don’t always need probable cause to seize evidence. The two most common exceptions to the probable cause requirement are (i) consent and (ii) the “plain view” doctrine:
- If the defendant freely consents to a search, the police don’t need probable cause to conduct it, and you may seize whatever incriminating evidence you find. Asking a defendant, “Can I look inside your trunk?”, for example, will justify an intrusion if the defendant says, “OK.”
- As long as an officer is somewhere they have a right to be, they can seize any evidence that is in plain view, as long as its incriminating nature is reasonably obvious. If a police officer, looking through your windshield, spots a baggie filled with white power on your dashboard, they can probably seize it even though they can’t be sure it’s not sugar.
These exceptions are not airtight, however. “Feel free to search my friend’s belongings,” for example, does not constitute valid consent.
The Exclusionary Rule
The exclusionary rule is a controversial, court-created rule of evidence. Under the exclusionary rule, a prosecutor cannot use illegally seized evidence against a defendant for the purposes of prosecution. Even if the police seize a metric ton of cocaine in the defendant’s backyard, they cannot use it as evidence if they searched for it or seized it in violation of the Fourth Amendment. If this leaves the prosecution with no viable case, they will drop charges.
The “Fruit of the Poisonous Tree” Doctrine
The “fruit of the poisonous tree” doctrine prevents the use of evidence that was obtained indirectly from the violation of a person’s Fourth Amendment rights. Following are two examples.
Invalid Arrest Warrant
A magistrate issues an arrest warrant based on inaccurate information (making the warrant invalid). The police arrest the suspect using an invalid warrant, search them incident to the arrest, and find a bag of illegal drugs in their pocket. The court should exclude the drugs from evidence because the seizure of the drugs was made possible by a body search that was justified using an invalid arrest warrant.
Invalid Search Warrant
A police officer lies to a magistrate in order to generate bogus probable cause for a search warrant. The magistrate, unaware of the falsehood, unintentionally issues an invalid search warrant. The officer searches the suspect’s home and uncovers a telephone address book containing the names of drug customers. The police elicit confessions from the customers that implicate the suspect. The prosecution cannot use the confessions against the suspect.
Contact a Criminal Defense Lawyer
Ohio criminal prosecutions are not for the faint of heart. If the police have arrested you or charged you with a crime, consulting the linked criminal defense resources might answer some of your questions. Ultimately, however, you probably need to seek a consultation with a seasoned criminal defense lawyer.