Search Warrant Requirements

The Fourth Amendment allows police to stop anyone in a public place who they suspect is participating in — or has just participated in — criminal activity. 

The Fourth Amendment to the United States Constitution guarantees the people's right to be free from unreasonable searches and seizures. This often means government agents must have a warrant to search and seize your person and property. Read on for important information about search warrant rules in the U.S.

Search Warrant Requirements and The Fourth Amendment

The Fourth Amendment to the U.S. Constitution states the following:

"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."

The Fourth Amendment protects people from unreasonable searches and seizures. This means that many government searches are legal if they meet specific guidelines. As a general rule, courts consider searches reasonable when:

  1. A judge issues a search warrant based on probable cause or
  2. Certain situations justify a search without a warrant

Probable Cause

Law enforcement officers must establish probable cause before legally searching and seizing property. To establish probable cause, a police officer must show the following:

  • Someone committed a crime at the place they will search or evidence of a crime exists at that location, and
  • It is more likely than not that a search will uncover evidence of the crime

Police must request the warrant in good faith. The requesting officer must also base their request on reliable information. Reliable information could include the following:

  • An officer's knowledge that someone committed a crime
  • An officer learns from a confidential informant that criminal activity occurred

Getting a Search Warrant

Once a law enforcement officer has probable cause, they must request a search warrant from a neutral judge or magistrate. The officer must draft an affidavit explaining why there is good cause to issue a search warrant. It should also explain why the search is necessary to further a criminal investigation.

The judge or neutral magistrate will issue or deny the search warrant. A search warrant is a court order. Search warrants must state with particularity where police can search. It must also state the specific parameters of the search. For example, it could clarify that police officers can only search the garage or the attic rather than the entire property.

Upon the warrant's issuance, police must present a copy of the warrant to the property owner. Police may then perform a search and seizure of the owner's property.

When the Fourth Amendment Does Not Apply

The Fourth Amendment's rules only apply when you have a reasonable expectation of privacy in a place or thing. So, if you don't expect privacy, the Fourth Amendment doesn't apply. In those cases, officers searching will not violate your constitutional rights.

The United States Supreme Court created a test for determining when a legitimate expectation of privacy exists. This test came from Katz v. United States in 1967. The test has two parts:

  1. Did the person subjectively expect the place or thing to be private (i.e., did they feel it would remain private)?
  2. Was that expectation objectively reasonable (i.e., would society agree that the place or thing should remain private)?

For example, most people believe that their homes are private. There is an expectation of privacy in one's home. Also, most people in society would find this expectation reasonable. So, a search of one's home by the police must meet the Fourth Amendment's reasonableness requirement.

Suppose someone leaves evidence of a crime on their front lawn in plain public view. A police seizure of that evidence would likely not constitute an unreasonable search. Most people would not expect an object visible to anyone passing by to remain private. Even if the homeowner genuinely expected that the area would remain private, that expectation would not be reasonable. So, the seizure would not violate the Fourth Amendment.

Warrantless Searches

Under certain circumstances, law enforcement can perform warrantless searches. These exceptions from the rule are to balance people's rights with the practical reality of law enforcement's duty to protect public safety. Warrantless searches can happen in the following circumstances:

Exigent Circumstances

Police may determine that circumstances are urgent enough to "justify a warrantless entry, search, or seizure." These are exigent circumstances. A court will decide, after the arrest, whether the whole of the circumstances justified the actions of the police. The court will consider, for example, the gravity of the offense or whether the suspect fled or tried to destroy evidence.

Emergencies that may justify a warrantless search include gunshots, screams, or fire inside a home.

Stop and Frisk (Terry Stop)

This is often called a stop and frisk or a Terry Stop. The procedure came from the case Terry v. Ohio in 1968. The officer can do a limited search of the suspect's outer clothing. The officer may also ask the suspect for identification.

To perform a stop-and-frisk, the officer must reasonably believe that the suspect is doing something criminal in a public place. The officer does not need probable cause to perform the search. Instead, they only need a reasonable suspicion that the suspect is committing or about to commit a crime.

A Terry stop is meant to protect officers from hidden weapons. So, if the police find contraband during the Terry stop, the officer cannot seize the contraband.

Police officers can ask for identification during a stop and frisk. The suspect does not have to show ID. But, if they refuse to show identification, and the police officer determines that the whole of the circumstances creates probable cause, the officer can arrest them. This became law in People v. Loudermilk in 1987.

Search Incident to Arrest

Police officers can perform a legal search incident to a lawful arrest. The Fourth Amendment allows an officer to search a suspect's person, clothing, and area within the suspect's immediate reach.

Suppose a police officer arrests a driver for driving under the influence (DUI). The officer can search areas of the vehicle within the driver's immediate reach, such as the front seats and the glove compartment. If the police officer has probable cause to believe there is evidence in the vehicle, such as an open liquor bottle, they can search the back seat. Moreover, if the police officer sees a liquor bottle in plain view, they can search the vehicle's interior. They could also search the entire vehicle if they have probable cause to believe contraband is in the car.

Felony Arrest in Public

Suppose an officer has probable cause to believe that a suspect committed a crime in a public place. They can then arrest someone without a warrant. For example, if the officer observed someone assault another person in public, the officer could arrest the suspect without a warrant.

If the suspect runs from police and enters a private home, the officer may need to get a warrant. But, if the officer is in "hot pursuit" of the fleeing felon, the Fourth Amendment allows them to arrest the suspect, even if the suspect flees to a non-public place. This became legal with Warden v. Hayden in 1967.

Peace officers (law enforcement officers) can also make warrantless arrests for misdemeanors committed in their presence.


If you consent to law enforcement's request to search your person or property, they can perform a warrantless search. You do not have to consent to a search just because a police officer asks. They can't perform a search without a warrant or another exception.

Who Does the Fourth Amendment Protect?

The Fourth Amendment's rules only apply to government actors. Private people do not fall under the Fourth Amendment's restrictions. For example, your Fourth Amendment rights do not apply if your neighbor searches your home. But, the search would violate your rights if your neighbor worked as a police officer for a law enforcement agency.

The government cannot present evidence discovered from an illegal search at trial. This "exclusionary rule" aims to deter police officers from conducting unreasonable searches. But, opponents of the exclusionary rule argue that it frees guilty criminals on technicalities.

Fruit of the Poisonous Tree Doctrine

Seized property gotten through illegal searches sometimes leads police to discover other evidence. But, when police take evidence while violating the Fourth Amendment, it is not accepted. This is the "fruit of the poisonous tree" doctrine. It prevents government actors from conducting unreasonable searches. If police know the court will exclude any evidence seized during an illegal search, they have an incentive to make sure the search is valid.

Here are a few examples to illustrate the exclusionary rule and the fruit of the poisonous tree doctrine:

Officer Joe suspects that Chris is selling drugs. Without a warrant, Officer Joe enters Chris' house and finds drugs and a scale on the kitchen table. Officer Joe also finds a map of locations throughout the city where Chris stores illegal weapons. Officer Joe collects the drugs, scale, and weapons and arrests Chris.

During an unlawful search, Officer Joe seized the map, drugs, and scale. The search was illegal because Officer Joe did not have a warrant, and a warrantless exception did not apply. So, the court will exclude these items because of the exclusionary rule. Officer Joe only discovered the illegal weapons because he found the map. The fruit of the poisonous tree doctrine prevents using the illegal weapons as evidence.

Just because the court excluded some evidence does not mean a judge will dismiss a case or that a jury will acquit the defendant. Prosecutors may still have enough other evidence to convict the defendant.

Prosecutors cannot use illegally seized evidence to secure a conviction. But, they may introduce it for other purposes. For instance:

  • The evidence may factor into civil and immigration cases
  • Prosecutors may use the evidence to attack the credibility of a witness
  • Judges may consider the evidence when determining a sentence after a conviction

Don't assume that a judge will always exclude illegally seized evidence. If the prosecutor uses the evidence, a judge will likely address it with a limiting instruction.

Talk to an Attorney about Search Warrant Rules

Criminal procedure and evidentiary rules are complex. Understanding your rights is critical to successfully navigating the district court system. A criminal defense attorney can give you information about the following:

  • General information about criminal cases, criminal law, and criminal procedure
  • Search warrants, arrest warrants, and law enforcement's execution of the warrants
  • Search warrants for cell phones

If you face criminal charges, consider speaking with a criminal defense lawyer to develop a defense strategy.

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