The Fourth Amendment Warrant Requirement

A warrant is a written court order signed by a judge or magistrate authorizing a law-enforcement officer to conduct a search, seizure, or arrest. The courts deem searches, seizures, and arrests without a valid warrant presumptively invalid. The judge will suppress any evidence the police seize without a warrant unless a court finds the search reasonable.

The Fourth Amendment to the United States Constitution applies to all governmental searches and seizures. Initially, this amendment only applied in federal cases. However, in Mapp v. Ohio, the Supreme Court extended this right to state courts.

The Fourth Amendment has two parts. The first part addresses the unreasonable search and seizure requirement, and the second includes the warrant clause. This amendment strives to balance government interests in preventing and investigating criminal offenses with the right of the people to be free from unreasonable intrusions.

The question is whether the police need a warrant to execute a search. The U.S. Supreme Court has ruled that Fourth Amendment protection expresses a preference that police conduct searches, seizures, and arrests pursuant to a lawfully executed search warrant.

Read on to learn about the Fourth Amendment warrant requirement and how it could apply to your criminal case.

Requirements for a Valid Search Warrant

The police who submit an affidavit supporting a warrant must attach a sworn, detailed statement. The officer must then appear before a neutral judge or magistrate. The judge will check to see if the officer has probable cause to execute the search.

In Carroll v. United Statesthe U.S. Supreme Court held that probable cause exists when a police officer has facts and circumstances that provide a reasonably trustworthy basis to believe a suspect has committed or is about to commit a crime.

If the police request a search warrant to search a location, the police must provide probable cause that evidence of a crime exists at that location. The officer must also state, with specificity, the items they are looking for.

Reasonableness Requirement

Even if the police have a warrant, their search must still be reasonable. Although the facts of the case dealt with a warrantless seizure, the court in Brinegar v. United States reiterated that the presence of a warrant does not give the police the power to conduct an unreasonable search.

The police officer's search must be reasonable, or the prosecutor won't be able to use the evidence they find in court. For example, if the police are looking for a large suitcase that contains drugs, it wouldn't be reasonable for them to look in your bedroom drawers. A large suitcase or duffel bag could not fit in a nightstand drawer.

Establishing Probable Cause

In Aguilar v. Texasthe court held that law enforcement can establish probable cause using out-of-court statements from reliable police informants. Probable cause will not exist where the only evidence of criminal activity is an officer's suspicion or belief that a suspect committed a crime.

When a judge determines probable cause, they will look at the totality of the circumstances. In Illinois v. Gates, the court held that there are no firm rules for establishing the probable cause requirement. Instead, law enforcement officers must use their objective knowledge and common-sense assessments to conclude that probable cause exists. The court will look at the totality of the circumstances surrounding the officer's basis for establishing probable cause necessary to obtain a warrant.

The courts have also held that probable cause is not the same as reasonable suspicion. Probable cause requires concrete facts that lead a police officer to suspect a person has committed or is about to commit a crime.

When justifying that there is probable cause to conduct a search, seizure, or arrest, the police may rely on:

  • Information provided by informants
  • The officer's observations
  • Observations of citizens

Once the judge or magistrate signs the warrant, the officer may proceed with their search.

An Officer's Oath

To establish probable cause for a warrant, an officer must submit, under oath, that the information they offer is true to the best of their knowledge. The officer's oath can be written or oral. The officer must confirm that they have not knowingly or intentionally made a false statement supporting the warrant. The officer must also swear they didn't make any statements in reckless disregard of the truth.

It's important to note that inaccuracies due to an officer's negligence or innocent omission won't typically jeopardize a warrant's validity. The Supreme Court has clarified that the warrant requirement exists to deter police misconduct. The government's goal is not to punish law enforcement officers or judges for errors.

Details in a Warrant Application

In addition to probable cause, the Fourth Amendment warrant requirement also requires the warrant to particularly describe the person or place to be searched or seized. In other words, warrants must provide enough detail that a judge and fellow officer can ascertain with reasonable effort the persons and places identified in the warrant.

For most residences, a street address satisfies the particularity requirement. If the police intend to serve the warrant at an apartment complex, hotel, or other multiple-unit building, the warrant must describe the specific unit the police plan to search.

Warrants must also describe individuals with sufficient particularity so that a person of average intelligence can distinguish them from others in the general population. In addition, the affidavit must identify the items the police plan to seize during the search.

Neutral and Detached Magistrate

The officer must request a warrant from a neutral and detached magistrate. As spelled out by the courts in California v. Acevedo, the magistrate must be impartial and not a member of the competitive enterprise of law enforcement. The law disqualifies police officers, prosecutors, and attorneys general from acting as a magistrate.

States vary as to the requirements for becoming a magistrate. Some states require that magistrates have an attorney's license, while others only demand that their magistrates be literate.

How Long Is a Search Warrant Valid?

When the police apply for a search warrant, they must execute it within a specific time. If this doesn't happen, they must return to the judge and get a new warrant issued.

The number of days a warrant remains valid varies from state to state. Generally, a search warrant is only good for 10 to 14 days. If the police can justify why they need more time, the judge will likely issue a new warrant based on the original affidavit.

Can the Police Execute a Warrantless Search?

Ideally, law enforcement officers will have a warrant before they search a person or their property. However, there are times when the police can search a place without a warrant. Whether the search will be lawful depends on the specific facts of the case.

Over the years, the courts have created exceptions to the warrant requirement. These include:

It is worth discussing each of these in detail. If the police searched you or your property, they must have a warrant or prove that one of the above exceptions applies. If you believe the police searched you without meeting these requirements, you should contact a criminal law attorney immediately.

Plain View

If the police see evidence of a crime in plain view, they can seize the item and search where they found it. For example, imagine the police pull you over for a routine traffic stop. They approach your car and see an open container of beer in your vehicle's center console. They also see a gun on the floor of the passenger seat.

These items are in plain view, and the officer can see them from outside the vehicle. In this situation, the police could seize the open container and the weapon. They could also search the car without violating your Fourth Amendment rights.

Exigent Circumstances

Law enforcement officers have a duty to protect citizens and ensure public safety. They are also required to investigate criminal activity and, when possible, prevent suspects from completing their crimes.

If the police can show that exigent circumstances exist at the time of their warrantless search, the search will likely be deemed lawful. For example, imagine that two police officers drive to the home of a person they suspect robbed a jewelry store.

When they knock on the suspect's door, they hear someone yelling that they have a hostage and a gun. The police have the authority to enter and search the home if only to protect the officers and others from harm.


Sometimes, a suspect gives the police officers consent to search their home, person, or vehicle. If this is the case, the police do not need a warrant. It will not be considered an unlawful search if the officers prove the homeowner consented.

While people have a reasonable expectation of privacy in their homes, that doesn't mean the police can never search their domicile. However, even if the person consents to a search, that does not give the police carte blanche authority to complete the search. The suspect can revoke their consent to search at any time. Additionally, the suspect may limit the search to certain areas in the home specified by the resident.

If the police continue to search despite this revocation, any evidence they find may be deemed inadmissible in your criminal trial. The suspect can argue that the police collected this evidence during an unreasonable search. The judge may toss out any evidence uncovered after the individual revoked consent.

The "Fruit of the Poisonous Tree" doctrine states that the court must exclude any evidence collected as a byproduct of an unreasonable search. This doctrine was born out of the exclusionary rule. The exclusionary rule dictates that the State cannot use evidence obtained during an unlawful search. If unlawfully obtained evidence leads law enforcement to additional evidence, it, too, would be inadmissible.

The person who consents to a police search does not have to own the property. The courts will likely deem the search lawful if the police had a reasonable belief that the person granting permission had the power to do so.

Search Incident to Arrest

Ideally, the police will have an arrest warrant before approaching a suspect. If so, they can perform a search incident to the arrest. For example, they can search the individual and area within their immediate control to see if they have contraband.

Even if the police don't have an arrest warrant, this exception will still apply. If the police can demonstrate that they had probable cause to believe the defendant committed a crime, the search will not be deemed illegal.

Stop and Frisk

If the police have reasonable suspicion that a person committed — or is about to commit — a crime, they are allowed to detain that individual for investigatory purposes. When they approach the suspect, they can do a cursory pat down to confirm the person has no weapons on them.

In Terry v. Ohio, the U.S. Supreme Court held that this type of limited search is lawful and does not violate a suspect's constitutional rights. If the police reasonably believe the suspect committed a crime, they can execute this brief stop. If, in good faith, the officer believes the suspect has a weapon on their person, they can pat down their exterior clothing.

Automobile Exception

Just like you have a reasonable expectation of privacy in your home, you also have a similar expectation of privacy in your vehicle. However, the right to privacy in your car or SUV is lower than the right to privacy in your home.

Law enforcement officers must follow specific rules before they may search your car. In Carroll v. United States, the court held that the police can search a vehicle without permission as long as they reasonably believe it contains contraband.

For example, imagine the police have a video of a getaway car used in a bank robbery. They can see the license plate on this getaway vehicle. The next day, they see this vehicle driving down a residential street. They pull the car over and conduct a warrantless search of the vehicle. The court will likely deem the search lawful since it is reasonable to think that suspects in an armed robbery would have weapons or contraband in their car.

It is essential to point out that the courts have held that there is no expectation of privacy in open fields. The police can search or follow a suspect into the woods, fields, and other like spaces.

Hot Pursuit

One final exception to the warrant requirement is when law enforcement officers are in hot pursuit of a suspect. In Warden v. Hayden, the court held that the police may enter a private home or business without a warrant if a felony had just occurred and the police chase the suspect from the place of the crime to the home or business.

The court's rationale for the hot pursuit rule is that a suspect shouldn't be allowed to avoid a lawful arrest simply because they were a step or two faster than law enforcement.

Learn More About Fourth Amendment Warrant Requirements: Talk to an Attorney

If the police search you or your property, they must follow specific rules of criminal procedure. If the police don't follow these rules, any evidence they collect during that search can be deemed tainted and not admissible in court.

Suppose you prove that police conduct in your case constituted a violation of the Fourth Amendment. In that case, the judge overseeing your criminal case will likely prohibit the state from using any evidence conducted in the illegal search.

A skilled lawyer knows what to look for with warrantless searches and can help you mount a strong defense. Contact a criminal defense attorney in your area who can help you understand any issues related to the warrant requirement.

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