Probable cause is a legal concept that’s applicable during several stages of the criminal justice process. It’s the standard judges use to evaluate the legality of police actions in arresting a suspect or conducting a search and to determine whether criminal charges can proceed to trial. This article provides an overview of what probable cause means in the various situations in which it applies.

What is Probable Cause?

Whether or not probable cause exists is determined on a case-by-case basis. Probable cause must be based on specific, articulable, and objective facts. While probable cause doesn’t require certainty, it does necessitate more than a “bare suspicion” or a “hunch.”

In determining whether probable cause exists, courts consider the totality of the circumstances. In other words, the relevant facts presented in support of probable cause are considered as a whole, instead of in isolation. The relevant circumstances must be evaluated based on common sense judgments and inferences.

When is Probable Cause Required?

Probable cause must be established to legally:

• make an arrest
• conduct a search and/or seize property
• obtain an arrest or search warrant, and
• charge a suspect with a crime.

In each of these contexts, the probable cause concept plays out a little different.

Probable Cause to Make an Arrest

An arrest with or without a warrant must be supported by probable cause. Generally, probable cause to arrest exists if the facts and circumstances would lead a reasonable person to believe an offense was committed and that the arrestee committed it.

The precise standards vary across jurisdictions, but in many states, for a warrantless arrest to be lawful:

• the officer must subjectively believe the person has committed a crime, and
• the officer’s belief must be objectively reasonable under the totality of the circumstances.

Similarly, before issuing an arrest warrant, a judge must determine there’s probable cause to believe that the person committed a crime.

If probable cause to make a warrantless arrest is challenged in court, a judge must decide whether—based on the officer’s articulation of the facts and circumstances existing at the time of the arrest—probable cause existed.

Probable Cause to Conduct a Search and/or Seize Property

Generally, a search and seizure conducted without a warrant is presumed to be unreasonable, unless an exception to the warrant requirement applies. Most searches and seizures—whether conducted pursuant to a warrant or within a permissible exception to the warrant rule— must be based on probable cause.

The probable cause analysis for obtaining a search warrant is the same analysis as for a warrantless search: There must be probable cause to believe the items sought will be found in the location where the search is conducted. Generally, probable cause exists when there’s a “fair probability” or “substantial chance” that evidence of a crime will be found at a particular location. Stated differently, there’s sufficient probable cause if the facts on which the officers relied would lead a reasonable person to believe that the items to be seized will probably be found in the location to be searched.

Search warrants. To obtain a search warrant, officers provide the judge with a sworn affidavit. The affidavit is usually in the form of a written statement, but in jurisdictions that allow telephonic warrants, the judge may take an oral statement under oath. A valid search warrant has several requirements, including a finding by the judge that there’s probable cause to believe that the search will discover the things specified in the affidavit.

Warrantless searches and/or seizures. In some situations, police can conduct a search and/or seizure without a warrant. Some of the more common warrant exceptions are:

• The automobile exception. Police can search a vehicle without a warrant if there’s probable cause to believe the vehicle contains evidence of a crime.
• Exigent circumstances. Some circumstances authorize a warrantless search to prevent danger to life, damage to property, a suspect’s escape, or the loss or destruction of evidence.
• Plain view exception. Police can search and seize property without a warrant if the officer is lawfully on the premises and it’s immediately apparent that the items in the officer’s view are evidence of a crime.

Basically, the warrant exceptions apply to various circumstances in which it would be impractical for the police to obtain a warrant before conducting the search or seizure.

Probable Cause for a Criminal Case to Proceed

In some jurisdictions, a preliminary hearing (also called a “probable cause hearing” or “evidentiary hearing”) is held after criminal charges have been filed. At the preliminary hearing, a judge determines whether there’s probable cause to support the charges against the defendant. If the judge decides there is probable cause to believe an offense has been committed and the defendant committed it, the case goes forward and the defendant must appear for further court proceedings. On the other hand, if the judge finds there isn’t enough evidence of the defendant’s guilt to establish probable cause, the charges are dismissed and the case ends there.