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What is Probable Cause for the Police to Arrest in Chicago?

December 10, 2020

You may have heard about the police wrongly arresting someone because they lacked “probable cause.” Or maybe you’ve heard about how the police need “reasonable suspicion” before stopping someone. Both of these terms represent important standards that are part of your constitutional rights. However, these two terms are often misunderstood, so let’s review them now.

What is Probable Cause?

Probable cause is a term that generally refers to police needing adequate information to arrest a suspect. This also means that police cannot just arbitrarily go and arrest someone, conduct a search, or seize property. They need to have at least somewhat of a reason to justify their actions.

“Probable cause” comes from the Fourth Amendment to the U.S. Constitution, which ensures that police cannot conduct unreasonable searches or seizures. An arrest or search without probable cause is considered constitutionally unreasonable.

Compare this to reasonable suspicion, which the police need before detaining someone. This is a lower bar, meaning the police need less evidence or suspicion to detain someone compared to arresting someone. You can read more about reasonable suspicion and when the police can legally detain someone here.

In short, in order to issue a warrant, arrest someone, or seize someone’s property, there must be a probable cause.

Probable Cause False Arrest

How and when is Probable Cause established?

Probable cause is established when a reasonable person — knowing what the arresting officer knows — believes the suspect has been, is, or is about to be, involved in criminal activity.

Police officers can’t establish probable cause only by saying, “the suspect looked like he was going to commit a crime.” For example, they can’t arrest a person claiming he was looking for drugs just because he roamed outside at 3 AM. That is not a reasonable basis by itself to arrest someone. There needs to be more.

Instead, the police need to identify specific facts and circumstances beyond a simple hunch or suspicion.

Police officers do not have the final say in determining whether there was legal cause to arrest; courts do. In order to establish probable cause, judges have to examine the known to the arresting officer at the time of the arrest.

An arrest without probable cause is a violation of your rights. If you believe that you or someone you know has been the victim of an unlawful detention or a false arrest, contact Chicago civil rights attorney Jordan Marsh for a free consultation at (224) 220-9000, or by email at

In sum, to establish legal cause to arrest, police officers need only enough information to establish a reasonable basis that the person committed or was about to commit a crime. They do not need enough information to prove legal guilt – that is a much higher burden.

When Does an Officer Need Probable Cause?

An officer needs to establish probable cause to do a number of important things. Let’s take a look at those situations now:

1. Obtain Warrants

A warrant is an authorization by a court for a police officer to take some specific action.

Warrants are typically issued before officers search someone’s home or property. Courts also issue warrants for the arrest of suspects if the officer seeking the warrant can establish legal cause for the arrest. (However, most arrests are made without warrants, although those arrests must also be supported by probable cause.)

The Fourth Amendment states that “no warrants shall issue, but upon probable cause.” Without it, there can be no warrant.

Generally, an officer can obtain a warrant by signing and presenting an affidavit to a judge for a search or an arrest. If the judge believes that the facts contained in the affidavit establish probable cause, the judge will sign the warrant, authorizing the officer to search or seize property, or to arrest a suspect.

2. Arrest

Remember, an officer can’t arrest someone based only on suspicion. The officer must be able to present enough evidence to lead to the reasonable belief that the suspect has committed, is committing, or is about to commit a crime.

Note that in the case of a warrantless arrest, the probable cause must be clear and concise. It should include ample information to allow the judges to evaluate the arrest. If the source of information is anonymous, the officer must include enough information to ensure that the witness is credible.

3. Search and Seize Property

The Constitution protects you against unreasonable searches and seizures, whether they be against you or your property.

If the police have a warrant, they can search a person or place and seize property in relation to a suspected crime. However, like arrests, a warrant might not be necessary to search or seize property.

Note that evidence seized in an illegal search becomes subject to the exclusionary rule and probably can’t be used against the defendant. The judge has the last say there.

Remember, you civil rights protect both your person and property. The Constitution limits the police from violating those rights.

Probable Cause FAQs:

Q. Can probable cause be based on hearsay?

A. Yes. Officers often rely on the statements of victims, witnesses, or other officers to provide probable cause to arrest a suspect, to or to search or seize property. However, the information must be credible enough that a reasonable officer would believe it.

Q. Does probable cause mean the suspect is guilty?

A. No. Guilt is determined by a judge or a jury after a trial, and can only be established by proof beyond a reasonable doubt. That is a higher standard than probable cause, which requires only a reasonable belief that the suspect committed or was about to commit a crime.

Q. Does an officer need probable cause to stop or detain someone?

A. No. In order to justify a temporary detention, also known as a “stop and frisk” or a Terry Stop, the officer needs only a reasonable suspicion that the person being detained was involved in criminal activity. This is a lower standard.

Q. Can probable cause be based on a hunch?

A. No. It requires objective facts — more than a hunch, more than just suspicion of illegal conduct.

Final Thoughts

As a general rule, probable cause provides the police the legal right to arrest someone, search a person or place, or seize someone’s property. It is established by a reasonable belief that the person committed a crime, or that the property to be searched or seized contains evidence of a crime.

Probable cause does not require proof of guilt beyond a reasonable doubt. Instead, it only requires the reasonable belief that a crime has been or is about to be committed.

Without probable cause or a warrant (which requires it anyways), an officer cannot arrest or search you. If that happens, realize that you have constitutional rights that may give rise to a claim against the officer.

The entire point of this standard is to protect your from government overreach. The Constitution sets out specific limits that police officers must follow. They are legally limited from arbitrarily searching you and your property. Similarly, the police cannot arrest you for no reason.

If you believe you have been a victim of a false arrest or an unreasonable search, contact Chicago civil rights attorney Jordan Marsh for a free consultation at (224) 220-9000, or at

The information provided on this website does not, and is not intended to,
constitute legal advice; instead, all information, content, and materials available on this site are for general informational purposes only. Use of and access to this website or any of the links contained within the site do not create an attorney-client relationship between you and our office.

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