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Difference Between Reasonable Suspicion and Probable Cause

Posted by Dmitry Gorin | Mar 14, 2024

To the layperson, the terms "reasonable suspicion" and "probable cause" sound similar—and some might even use these terms interchangeably. However, the legal meanings between these two are different. 

Understanding these concepts and their differences may be fundamental in determining the legality of police actions like stops, searches, arrests, and more. Knowing whether law enforcement acted upon reasonable suspicion or probable cause could significantly impact your defense strategy if you are charged with a federal crime.

Difference Between Reasonable Suspicion and Probable Cause
Reasonable suspicion and probable cause are similar, but there are important differences.

Probable cause generally means that a reasonable person would believe that a crime was in the process of being committed, was already committed, or was going to be committed. Probable cause is typically enough for a search or arrest warrant and for a police officer to arrest if they observe a crime being committed.

The United States Supreme Court has described reasonable suspicion as a common-sense conclusion about human behavior upon which practical people are entitled to rely. Simply put, reasonable suspicion requires more than a “hunch,” but rather facts or circumstances that give rise to more than a bare suspicion.

Reasonable suspicion means that a reasonable person would suspect that a crime was in the process of being committed, had already been committed, or would be committed soon.

Suppose a police officer has reasonable suspicion. In that case, they can briefly frisk or detain the suspect. However, reasonable suspicion does not allow searching for a person or a vehicle unless they are on school property. Reasonable suspicion is not enough to obtain an arrest or a search warrant.

On the controversial issue of stop and frisk, in Terry v. Ohio, 392 U.S. 1 (1968), the court recognized that a limited stop and frisk of someone could be conducted without a warrant based on less than probable cause. 

However, the stop must be based on a reasonable, individualized suspicion based on articulable facts, and the frisk is limited to a pat-down for weapons. Thus, an anonymous tip that somebody is carrying a weapon is insufficient to justify a stop and frisk. 

What is Reasonable Suspicion?

Reasonable suspicion is a legal standard that allows law enforcement officers to briefly detain and question individuals with specific, articulable reasons to suspect criminal activity. 

In simple terms, "reasonable suspicion" is when a police officer has a good reason to suspect someone of criminal activity based on specific facts. It's like suspicion backed by facts that allows them to stop and sometimes search.  For reasonable suspicion to apply, the officer's actions should be based on objective facts and rational inferences, not mere hunches or intuition.

For instance, suppose an officer observes someone loitering around a closed store late at night, repeatedly glancing at the entrance. Here, the officer could reasonably suspect that a crime might be imminent, which permits them to stop and question the individual.

The terms probable cause and reasonable suspicion are often confused and misused. While both have to do with a police officer's overall impression of a situation, they have different repercussions on the following:

  • Someone's rights,
  • The proper protocol and
  • The outcome of the situation.

Reasonable suspicion is a step before probable cause. At the point of reasonable suspicion, it appears that a crime might have been committed. The situation escalates to probable cause when it becomes clear that a crime has most likely been committed.

What is Probable Cause?

Probable cause is a higher legal standard than reasonable suspicion. It allows law enforcement officers to obtain a warrant, conduct personal or property searches, or arrest a suspect. 

Probable cause requires more than just suspicion; there must be enough evidence or information to suggest that a person has committed a crime. In other words, the facts must be strong enough to lead a reasonable person to believe that the accused party is guilty.

For example, suppose an officer stops a vehicle for a traffic violation and visibly notices a suspicious-looking stash of plastic bags in the backseat. In that case, the officer has probable cause to search the car for illicit controlled substances and possibly arrest the driver. Notably, consider the issue of probable cause in the following situations:

  • To obtain a search warrant, the court must consider whether, based on the totality of the information, there is a fair probability that contraband, evidence, or a person will be found in a particular place.
  • To arrest a suspect, the police officer must have a good faith belief that a crime has been committed and the person they are arresting committed the crime.

Why Is Understanding the Difference Important?

The main difference between reasonable suspicion and probable cause is what each authorizes law enforcement to do. An officer only needs reasonable suspicion to stop, question, and possibly frisk for weapons. 

However, an officer cannot arrest you based only on reasonable suspicion, nor can they search your vehicle or property. To take these actions, the officer must have probable cause—and for the officer's actions to hold up in court, probable cause must be aptly demonstrated. 

Here's a broader summary of the differences between reasonable suspicion and probable cause and how these two concepts sometimes work together:

  • Origin of Action: Reasonable suspicion is based on specific, articulable facts that suggest criminal activity might be afoot, allowing law enforcement to initiate a brief stop and question. Probable cause, however, requires more concrete evidence indicating that a crime has been committed, which can justify an arrest, search, or warrant.
  • Degree of Certainty: Reasonable suspicion requires lower certainty and relies mainly on the officer's subjective assessment and inference from the situation. Probable cause demands a higher level of certainty, where the facts would lead a reasonable person to believe that the accused party is guilty.
  • Legal Consequences: Actions taken under reasonable suspicion may lead to discovering evidence that could establish probable cause. However, actions taken under probable cause can lead directly to charges, trial, and potential conviction.
  • Protection of Rights: Both standards are designed to safeguard citizens' rights, but probable cause provides a more robust protection against unreasonable searches and seizures as it requires more substantial evidence.
  • Court Review: Courts scrutinize actions taken under probable cause more closely than those under reasonable suspicion, given the greater potential infringement on personal rights associated with the former.

How Can These Concepts Apply to Your Defense?

For those accused of federal crimes, understanding the distinction between these legal standards helps you recognize when law enforcement actions are legally justified and when they may infringe upon your rights. It can also significantly affect the admissibility of evidence and the legality of law enforcement actions in your case. 

A federal criminal defense attorney can strategically leverage the concepts of reasonable suspicion and probable cause to protect your rights. 

If your attorney can demonstrate that investigators or law enforcement overstepped their bounds—for instance, conducting a detailed search based only on reasonable suspicion—any evidence obtained during this process could be deemed inadmissible in court.  Contact our law firm for further information. Eisner Gorin LLP has offices in Los Angeles, California.

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About the Author

Dmitry Gorin

Dmitry Gorin is a licensed attorney, who has been involved in criminal trial work and pretrial litigation since 1994. Before becoming partner in Eisner Gorin LLP, Mr. Gorin was a Senior Deputy District Attorney in Los Angeles Courts for more than ten years. As a criminal tri...

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