When the Fourth Amendment Applies

The Fourth Amendment protects people from unreasonable searches and seizures. It only applies to government action. This includes the actions of law enforcement officials like police officers and FBI agents. But it technically applies to all government employees, such as postal workers and public school administrators. 

The Fourth Amendment to the United States Constitution applies in many different situations. Generally, the Fourth Amendment applies to the following:

While its application may seem straightforward, the Fourth Amendment has given rise to extensive litigation. For example, the U.S. Supreme Court has had to answer the following questions:

This article discusses the circumstances in which the Fourth Amendment applies. It begins by summarizing the Fourth Amendment protections, including a brief history of its application. Then, it discusses searches, seizures, and search warrants. Finally, it discusses the effect of illegal searches.

Entire law school textbooks and courses cover the Fourth Amendment's protections. The protections and exceptions are complex, even for legal professionals. For more information, check out FindLaw's Criminal Rights section. Or, consider contacting a criminal defense attorney near you.

When the Fourth Amendment Applies: Background

The Fourth Amendment to the U.S. Constitution says 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."

This also means your nosy neighbor does not violate your Fourth Amendment rights by rifling through your things (although they most likely violate state law).

The Fourth and Fourteenth Amendments

Like the rest of the Bill of Rights, the Fourth Amendment to the U.S. Constitution originally only applied in federal court. This changed in the U.S. Supreme Court case Mapp v. Ohio (1961). There, the Supreme Court ruled that the Fourth Amendment rights apply equally in state courts through the Fourteenth Amendment.

The Fourteenth Amendment guarantees the right to due process and equal protection of the laws. This process, known as the doctrine of incorporation, applies most, but not all, of the Bill of Rights' liberties to the states.

Searches and Seizures

It's important to know that not every search and seizure scrutinized in state and federal court raises a Fourth Amendment issue. The Fourth Amendment only protects against the government's searches and seizures.

So, the Fourth Amendment does not govern surveillance and investigatory actions taken by strictly private persons, such as private investigators, suspicious spouses, or nosy neighbors. But, Fourth Amendment concerns arise when law enforcement, or a private person working in conjunction with police, takes those same actions.

The Fourth Amendment doesn't apply to every governmental search. If the person searched did not have a reasonable expectation of privacy in the place the government searches (or the item the government seizes), there is no Fourth Amendment violation. The Fourth Amendment only protects against unreasonable searches.

When Is There a Reasonable Expectation of Privacy?

Of course, the Fourth Amendment doesn't automatically invalidate governmental searches and seizures. Defendants must first establish that they had a reasonable expectation of privacy in the place or thing the government searched or seized. This leads to the following questions:

  • What is an expectation of privacy?
  • When is that expectation reasonable?

About the expectation itself, the Supreme Court has explained that what "a person knowingly exposes to the public, even in his own home or office, is not a subject of Fourth Amendment protection. But what he seeks to preserve as private, even in an area accessible to the public, may be constitutionally protected."

Applying this principle, the Supreme Court has ruled that people have a reasonable expectation of privacy in their bodies, clothing, and personal belongings.

Homeowners have a privacy interest that extends inside their homes and in the curtilage immediately surrounding the outside of their homes. The Court has ruled that homeowners do not have an expectation in "open fields" and "wooded areas" extending beyond the curtilage. While people have a reasonable expectation of privacy in cars, the expectation of privacy is less than a homeowner's privacy interest in their home.

A business owner's expectation of privacy in commercial property is less than the privacy interest afforded to a private homeowner. A business owner's expectation of privacy is lower in commercial property used in "closely regulated" industries such as:

  • Airports
  • Railroads
  • Restaurants
  • Establishments that sell liquor

These establishments have less privacy protection because they are subject to regular administrative searches by state or federal agencies. The government performs these routine searches to determine compliance with industry regulations.

Standing and the Fourth Amendment

A person must have standing to raise a Fourth Amendment objection to a search or seizure. Standing in this context means that the rights guaranteed by the Fourth Amendment are personal. You can't assert them on behalf of others. For example, a passenger may not object to a police search of the owner's car.

A guest may not object to a search of a homeowner's premises. But these rules can become murky when a guest is living with or renting from the homeowner. Questions also arise if the guest owns or stores things on the owner's premises.

When Isn't There a Reasonable Expectation of Privacy?

Generally, a person has no reasonable expectation of privacy for property and personal effects they hold open to the public. The Fourth Amendment does not protect things that are visible or in "plain view" for a person of ordinary and unenhanced vision. Items lying in someone's backseat, growing in someone's outdoor garden, or discarded in someone's curb-side garbage do not fall within the Fourth Amendment protection.

But suppose the government seizes items they became aware of through enhanced surveillance. Such enhanced surveillance may include the use of high-powered or telescopic lenses. These may be subject to Fourth Amendment requirements without a valid search warrant.

Things readily accessible to the public enjoy no expectation of privacy. For example, the Fourth Amendment does not protect public records and published phone numbers.

Bodily Samples Subject to Fourth Amendment Protection

The Supreme Court has said that people do not have an expectation of privacy in their personal characteristics. So, the police may require people to give handwriting samples, for example.

Police may also take the following bodily samples, among others:

  • Hair
  • Blood
  • DNA
  • Fingerprints

For example, police may take a blood sample following a DUI traffic stop. But they may request the suspect provide a breath sample, often into a breathalyzer. The blood and breath samples are searches subject to 4th Amendment protection.

The Fourth Amendment protects against government intrusion upon one's body. But, implied consent laws in every state carry penalties related to a motorist's refusal to provide such samples. When a motorist applies for a driver's license, they give implied consent to submit to field sobriety tests meant to determine impairment. These laws typically impose a penalty on motorists who refuse such tests.

Search Warrants

T government must have a search warrant to perform a valid search. A search warrant is a court order from a neutral judge or magistrate. It specifies the specific area police may search. It also sets out the parameters of the search. But there are many exceptions to the general warrant rule.

Law enforcement must prove to the judge that probable cause exists before the judge issues a warrant. Probable cause requires law enforcement to show the following:

  • They have a reasonable belief that a crime occurred; and
  • The subject of the search warrant committed the crime, or there is evidence of the crime at the location.

So, law enforcement must have more than mere suspicion that a person committed a crime. The police officer must base their opinion on specific facts or knowledge. Typically, a law enforcement officer will provide the judge with an affidavit containing this information. The judge then decides whether to issue the search warrant. The judge bases their decision on the totality of the circumstances presented.

Exceptions to the Warrant Requirement

There are several exceptions to the general warrant rule. Law enforcement's search may be valid without a warrant in certain circumstances. We'll describe these exceptions below.

  1. Exigent circumstances: Law enforcement doesn't need to get a search warrant in an emergency. For example, if they believe that a suspect will destroy evidence of a crime if police don't perform a search, they may search without a warrant.
  2. Stop and frisk: A police officer can perform a pat-down search of a person they believe participated in criminal activity. The search is limited, as law enforcement may only search for weapons. Such a search is also known as a Terry stop, from the Supreme Court case Terry v. Ohio (1968).
  3. Search incident to arrest: After a lawful arrest, a police officer may search the suspect and their immediate surroundings. If the police make an arrest following a traffic stop, they may search the arrestee's vehicle in some situations. For example, if they believe they may find evidence of criminal activity in the vehicle, they can search it. Police only need a reasonable suspicion of criminal activity to do a traffic stop.
  4. Plain view: As noted above, police may seize contraband in their plain view.
  5. Consent: If law enforcement asks to search you or your belongings, and you consent to the search, they can perform it without a warrant.

For more specific information about these exceptions, browse FindLaw's Criminal Rights section.

Illegal Searches

Suppose law enforcement searches your person without a warrant; no exception applies. They ultimately arrest you and intend to use the incriminating evidence they found in your criminal case. What happens then?

The Fourth Amendment's exclusionary rule prohibits the prosecution from using illegally obtained evidence in a defendant's criminal trial. The rule bars the trial court from admitting such evidence at trial. So, if an illegal search of your home results in law enforcement finding incriminating evidence, the exclusionary rule will bar the evidence from your trial.

The exclusionary rule is not the only protection against illegal searches. The “fruit of the poisonous tree" doctrine prevents trial courts from admitting further evidence seized due to an unreasonable search.

For example, suppose law enforcement illegally searched a defendant's home. During the search, they found a map indicating illegal weapon caches hidden throughout the county. If law enforcement seizes these, the fruit of the poisonous tree doctrine will bar them from admittance at trial. This is because law enforcement would not have known about the caches but for their illegal search.

Have Specific Questions About When the Fourth Amendment Applies? Ask an Attorney

The Fourth Amendment's protection against unreasonable searches and seizures is complex. If the government has charged you with a crime related to a search, consider contacting a local criminal defense attorney. An experienced attorney can give you legal advice about the following:

  • Defense and litigation strategy about your pending misdemeanor or felony criminal case
  • General information about criminal law
  • An overview of your constitutional rights
  • Whether law enforcement's search violated your Fourth Amendment protections

Handling a criminal case on your own is a daunting task. Contact a criminal defense lawyer near you today to protect your interests.

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