Probable Cause Definition

Probable Cause Attorney | Probable Cause Lawyer | Criminal Defense LawyerProbable cause is a term that is used often in criminal law. At its core, the term allows a police officer to arrest or search someone without a warrant and it is required before a judge can issue an arrest warrant. Probable cause is also required before a grand jury can return an indictment. There’s more on the topic on this page check it out!
The requirement that police act with probable cause comes from the 4th Amendment, which states:

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 seized.

What is the Definition of Probable Cause?

Although probable cause is a term that is used often in the criminal law, it does not have a fixed definition. A common definition used by the courts is “a reasonable amount of suspicion, supported by circumstances sufficiently strong to justify a prudent and cautious person’s belief that certain facts are probably true.” This definition is painfully vague. It does not require the police officer to be confident that he or she is right nor does it require the police officer’s judgment to be ultimately correct. Indeed, probable cause can be found when a police officer makes a mistake as long as the mistake was reasonable. The definition allows a police officer to use his or her knowledge and experience in making the probable cause determination. Ultimately, probable cause exists when the facts and circumstances are sufficient to warrant a prudent person to believe that a person has committed, is committing, or is about to commit a crime.

How Can Probable Cause Be Established?

Probable cause exists when the police officer has sufficient facts to justify a stop or search. To warrant the search or seizure the police officer’s actions must be based upon actual facts and circumstances that would lead a reasonable officer to believe that criminal activity has occurred or is about to occur.

To satisfy the probable cause requirement a police officer is allowed to his or her personal observations; hearsay statements made to the officer; the officer’s expertise; and any circumstantial evidence available at the time of the search or seizure.

What Happens When the Police Conduct an Arrest or a Search Without Probable Cause?

Probable cause is a term that dominates 4th Amendment law. All warrantless arrests and searches must be conducted within the confines of the Constitution. The courts struggled to fashion an appropriate remedy for police that violated a person’s Fourth Amendment protections. Ultimately, the Supreme Court held that all evidence that was obtained as a result of a 4th Amendment violation must be suppressed and unavailable as evidence in any future prosecution. This drastic remedy is known as the exclusionary rule.

The exclusionary rule acts as a deterrent to future police behavior. The exclusionary rule not only suppress the evidence that was seized at the time of the illegal search or arrest but any evidence that was obtained following the illegal search or seizure. Of course, there are numerous exceptions to the exclusionary rule and evidence that is attenuated from the 4th amendment violation or evidence that would have been discovered regardless of the probable cause violation can still be used by the prosecution.

What is a Suppression Hearing?

The exclusionary rule does not automatically apply. In fact, the United Supreme Court has said that the exclusionary rule should be used only when the suppression will deter future police action. A defendant seeking to invoke the exclusionary rule must first file a motion to quash arrest and suppress evidence. The trial court will then conduct a hearing and receive evidence at the hearing. The defendant must establish that his or her 4th Amendment rights were violated by the police action. If the defendant is successful, then the prosecution must rebut the defendant’s evidence by a preponderance of the evidence.


Probable cause is a very fact-based legal term. Case law is filled with cases that are identical that have reached a different result on the legality of a warrantless arrest or search. Most of the time, the difference in results is the ability of the criminal defense attorney to establish a 4th amendment violation.

Jaleel Law P.C. has the experience to properly handle suppression hearings and the know-how to present the evidence in the effective and persuasive manner. If you have been arrested for any crime without a warrant, you may have a successful suppression motion based upon a lack of probable cause. Contact Jaleel Law P.C. to discuss your situation and how we can help.