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What Is Probable Cause?


Under the Fourth Amendment, it is “the right of the people to be secure in their persons, house, papers, and effects, against unreasonable searches and seizures,” and this right “shall not be violated, and no warrants shall issue, but upon probable cause.” That means law enforcement officers must have evidence or facts that lead to the reasonable belief a crime has been committed; they cannot base an arrest or search on feelings, instincts, or suspicion. When deciding whether an arrest or search was made legally, courts will consider whether a reasonable person in similar circumstances would have believed a crime was being or had been committed.

There are four ways in which probable cause can be established:

  • Observational evidence: based on what the officer sees, hears, or smells
  • Circumstantial evidence: based on facts that indirectly suggest a crime has occurred, and is usually examined in conjunction with other pieces of evidence
  • Officer expertise: based on the officer’s training for detecting that a certain activity occurred, such as drug detection specialists who can determine if a person has an illegal substance in their system
  • Informational evidence: based on statements made by victims, witnesses, or informants

Probable Cause and Arrests

When an arrest is made, all information related to the arrest will be considered in total to determine if probable cause existed. If an officer makes a warrantless arrest without first having a reason to support their actions, any evidence collected may not be admissible in court.

Probable Cause and Searches

In general, an officer must have probable cause to search an individual’s personal property, such as a home. The officer must submit an affidavit to the court stating the grounds for conducting a search.

Under some circumstances, an officer can conduct a warrantless search, but the officer must testify in court as to why the search was conducted. In most cases, an officer can search an individual’s vehicle without first obtaining a warrant if the officer believes a criminal act has occurred or is likely to occur. A vehicle search conducted without a warrant is generally justified in that a person drives on public roads so any privacy interests are reduced.

Contact Bridges, Jillisky, Weller & Gullifer, LLC for a Free Consultation

If you’re facing criminal charges, contact our skilled team for competent legal counsel. We will take the time to thoroughly investigate your case and determine how evidence was collected to ensure your constitutional rights were not violated.

To get started, call us at (937) 403-9033 or contact us online.