Anyone who has watched an episode of any law show on television has likely heard the term “probable cause” bandied about. This is a very important legal term in criminal law. The Fourth Amendment to the United States Constitution guarantees each citizen security in their persons, houses, papers and effects, against unreasonable searches or seizures by police. 

In other words, a police search or seizure must be reasonable, or it is illegal. If an officer gets a warrant based on probable cause, then the search or seizure is presumptively reasonable. 

How does the law define probable cause? 

The fourth amendment clarifies that probable cause is a critical element in controlling police infringement upon personal liberties. What exactly is the definition of probable cause, though? 

Probable cause to search or seize exists when an officer can articulate facts that suggest someone committed a crime. Typically, the officer must apply to the courts to get a warrant based upon probable cause. A judge will then review the facts and decide if he or she agrees with the officer that probable cause exists. 

If in agreement, the judge issues a warrant that specifies the searchable or seizable persons, places or property. Bypassing this warrant requirement can only happen legally when: 

  • An officer gets consent to search 
  • An officer searched the immediate area of someone legally arrested 
  • Evidence of a crime is in plain view of the officer 
  • A person is in their vehicle where there is a lesser expectation of privacy 
  • There is an emergency 

What happens if an officer performs a search or arrest without probable cause? 

The United States Supreme Court carved out the “exclusionary rule” to deal with unreasonable searches and seizures. What this means is that if an officer searches or arrests an individual without probable cause, a lawyer can likely suppress the resulting evidence. Many times, if the judge grants the suppression of critical evidence, the prosecutor drops the charges.