The Fourth Amendment Reasonableness Requirement and Warrantless Searches

The U.S. Supreme Court has ruled that some warrantless police searches may comply with the Fourth Amendment. These exceptions reflect the court's reluctance to impede the job of law enforcement officials.

The Fourth Amendment to the U.S. Constitution protects citizens from unreasonable searches and seizures by the government. Government searches include any searches a city, state, or federal government agent performs. The Fourth Amendment protections apply to the states through the Fourteenth Amendment.

Generally, the government needs a search warrant, an arrest warrant, or probable cause to perform a valid search or seizure. However, there are some exceptions to the general warrant requirement. If an exception applies, a warrantless search may still be reasonable.

This article discusses the warrant requirement, warrantless searches, and specific exceptions to the requirement. For more information, consider reviewing FindLaw's Criminal Rights section.

The Warrant Requirement

The Fourth Amendment generally requires government officials to obtain an arrest warrant or search warrant to execute a valid search and seizure. A police officer must fill out an affidavit and present it to a neutral judge or magistrate to obtain a warrant. The officer must make a showing of probable cause and explain why they believe the search will yield evidence of criminal activity. The judge or magistrate will then decide whether to issue the warrant.

Many searches performed without first obtaining a warrant are unconstitutional. If law enforcement obtains evidence illegally, the exclusionary rule applies. This rule prevents the prosecution from using illegally obtained evidence in a criminal trial. However, there are some exceptions to the warrant requirement.

What Is a Warrantless Search?

Any governmental search of a person or property without a warrant is a warrantless search.

Typically, the Fourth Amendment protects against warrantless searches. But there are exceptions to the warrant requirement.

The warrant exceptions strike a balance among:

  • The government's interests
  • The practical realities of daily police work
  • The right of the people to privacy and freedom

Suppose the law always required police officers to complete a warrant application before they could search or seize a suspect or evidence. It would require them to appear before a judge and await their decision regarding the warrant. The likely result would be the destruction of evidence or suspects disappearing. The circumstances under which the law deems a warrantless search, seizure, or arrest reasonable generally fall within the following seven categories:

  • For a felony arrest in a public place
  • When directly related to a lawful arrest
  • During a traffic stop for reasonable suspicion
  • With someone suspected of ongoing criminal activity
  • Under so-called exigent circumstances
  • At certain roadside checkpoints
  • When made in good faith under a warrant later ruled invalid

Felony Arrest in a Public Place

Law enforcement does not need a warrant for a felony arrest in a public place, even if the arresting officer has time to get a warrant. If the officer has probable cause that the suspect committed a crime, the officer may make a valid arrest.

Felony arrests in places not open to the public generally require a warrant. Typically, a police officer cannot enter a suspect's home and arrest them without a warrant. However, if the officer is in hot pursuit of a fleeing felon, they may enter a residence without a warrant.

The Fourth Amendment also allows warrantless arrests for misdemeanors committed in an officer's presence.

Searches Directly Related to a Lawful Arrest

Police do not require a warrant for searches incident to a lawful arrest. If a police officer makes a lawful arrest, the Fourth Amendment permits them to search the following:

  • The suspect's person
  • The suspect's clothing
  • All areas within the suspect's immediate reach

This kind of warrantless search is justified because it allows police officers to protect themselves from suspects who may have hidden weapons. However, officers are only permitted to seize items from the area in the arrestee's immediate control.

Traffic Stops for Reasonable Suspicion

An officer may stop a motor vehicle if they possess a reasonable and articulable suspicion that the motorist has violated a law. The Fourth Amendment permits the officer to search the vehicle's interior so long as they have probable cause. Such a search may include the vehicle's glove compartment.

Law enforcement officers typically cannot search the vehicle's trunk. That changes if they have probable cause to believe it contains contraband or evidence of criminal activity.

Once law enforcement impounds a vehicle, they may inventory its contents without a warrant, including the trunk's contents. Also of note, police may seize contraband that is in plain view. Plain view means that the officer easily observes incriminating evidence. The police officer must be acting according to proper procedure. For example, if they notice a duffel bag labeled “illegal drugs" in the back seat of the vehicle they pulled over, they can seize the bag.

Suspects of Ongoing Criminal Activity

An officer who reasonably believes criminal activity is afoot in a public place is authorized to stop any person they suspect is participating in such activity. The police may conduct a carefully limited search of the suspect's outer clothing for weapons that may be used against the officer.

Such a stop is also known as a stop and frisk or a Terry stop, after the U.S. Supreme Court case Terry v. Ohio (1968). A Terry stop is designed to protect officers from hidden weapons. Accordingly, law enforcement can only seize weapons during such a search. They cannot legally seize anything else, even if it turns out that the item is contraband. The exception is if they seize a container large enough to hold a weapon. If the police officer opens the container and, instead of a weapon, finds contraband, they may seize the contraband and charge the individual.

The officer may also ask for identification during a stop and frisk. The suspect typically does not have to produce it. However, a suspect's refusal to produce identification, together with surrounding events, may create probable cause to arrest.

Exigent Circumstances

Warrantless searches, seizures, and arrests may be justified by exigent circumstances. To determine whether they justified police conduct, a court reviews the totality of the circumstances. For example, it may include an analysis of the underlying offense and whether the suspect was fleeing or trying to escape. The surrounding circumstances must be tantamount to an emergency. For example, courts have considered the following circumstances as exigent:

  • Gunshots
  • Screaming
  • Fire emanating from inside a building

In such situations, police officers may dispense with the Fourth Amendment's warrant requirement.

Certain Roadside Checkpoints

The U.S. Supreme Court has upheld brief, warrantless seizures at certain fixed roadside checkpoints. For example, it has upheld such searches aimed at intercepting drunk drivers and illegal border crossings.

Law enforcement must tailor roadside checkpoints to remedy specific problems. The problems must be ones that they cannot effectively address through more traditional means. For example, problems relating to policing the nation's border and ensuring roadway safety are valid reasons for using checkpoints.

When a checkpoint's primary purpose is to detect ordinary criminal activity, the Supreme Court has declared that it violates the Fourth Amendment.

Reasonable Searches and Good Faith

Government searches, seizures, and arrests made pursuant to a defective warrant may be justified if the officer was proceeding in "good faith."

The Supreme Court said in United States v. Leon (1984) that law enforcement's search pursuant to a warrant that a court later declares invalid (i.e., it fails to meet the requirements for a valid warrant) is still considered reasonable if both of the following elements are met:

  1. A neutral judge or magistrate issued the warrant.
  2. The police did not willfully deceive the judge or magistrate.

This exception to the warrant requirement was created to protect honest police officers who did nothing wrong while acting on an ostensibly valid warrant.

Protect Your Fourth Amendment Rights With Legal Counsel

The Fourth Amendment contains significant protections against abuse by law enforcement. However, many exceptions allow for the warrantless collection of evidence against you.

Challenging the government's search and seizure of incriminating evidence is difficult. One of the many challenges includes establishing that you had a reasonable expectation of privacy in what was searched or seized. However, if you can establish a violation of your constitutional rights, it can have a significant impact on your case.

Contact a criminal defense attorney if you believe the government violated your Fourth Amendment rights. An experienced attorney can provide you with valuable legal advice and information regarding the following:

If you are facing criminal charges, do not delay in contacting a criminal defense attorney.

Was this helpful?

Can I Solve This on My Own or Do I Need an Attorney?

  • Complex criminal defense situations usually require a lawyer
  • Defense attorneys can help protect your rights
  • A lawyer can seek to reduce or eliminate criminal penalties

Get tailored advice and ask your legal questions. Many attorneys offer free consultations.


If you need an attorney, find one right now.