4th Amendment

The meaning of the 4th Amendment comes from unlawful searches and seizures. For example, the 4th Amendment protects people from the unlawful search and seizure by police of their persons, their homes, and their belongings. If an officer violates the 4th Amendment, the victim can sue for wrongful arrest, among other things. To explore this concept, consider the following 4th Amendment definition.

Definition of 4th Amendment


  1. The amendment to the U.S. Constitution that protects Americans from unlawful search and seizure by police.


September 25, 1789

What is the 4th Amendment?

The 4th Amendment is the amendment to the U.S. Constitution that protects American citizens from unlawful searches and seizures. What this means is that the police cannot arrest an individual without a warrant or probable cause, and they cannot take a person’s home or property either without valid reason. Unfortunately, 4th Amendment examples of violations happen every day in the U.S. In many of these cases, the victim will sue the police upon his release from prison, and/or to reclaim his property.

Requirements of the 4th Amendment

There is a lot of debate regarding the proper requirements of the 4th Amendment, and it has to do with the definition of “reasonable,” and “probable cause.” In most cases, there is a strict requirement that law enforcement have a search warrant before searching, though in some specific instances, probable cause to believe a suspect is doing or hiding something illegal is enough.

Probable cause that allows police to search a person’s belongings or person includes such things as the strong smell of marijuana emanating from a car a police officer has just stopped. This would give the officer reasonable belief that there is an illegal drug in the vehicle, and therefore probable cause to search the vehicle – and the driver’s person as well.

Ultimately, the 4th Amendment is in the Constitution to protect Americans’ rights. It is there to protect people from the government’s intrusion upon their lives unless the government has a good reason to intrude.

Unreasonable Search and Seizure

An unreasonable search and seizure is a search and seizure that invades a person’s privacy. For instance, searches of people’s garbage are not 4th Amendment examples of unreasonable search and seizure because the individual put the bags at the curb. Once the garbage bags are on the side of a public road, they are accessible to everyone from animals and children, to scavengers and snoops. So, if the police go through a person’s garbage and find incriminating evidence, this is not an instance of an unreasonable search and seizure.

This is also the reason why a person who consents to a search or voluntarily provides evidence to the police should not have a reasonable expectation of privacy. He is inviting others to explore what he has to offer. Therefore, it is not unreasonable for those people to dig deeper and potentially uncover more information.

Reasonable Search

The 4th Amendment states that one way in which the police can conduct a reasonable search is to obtain a legitimate warrant. The warrant must describe the place the police wish to search, as well as the people they intend to arrest and the property they intend to seize. Another way they can conduct a reasonable search is to require that the search meets the parameters of an exception to the rule requiring warrants.

Essentially, the way to define a reasonable search is to compare the government’s interests with a person’s reasonable expectation of privacy. For instance, examples of 4th Amendment violations are less likely if a person is guilty of a violent crime. If someone commits a serious crime, he should not expect to enjoy his privacy for very long before the authorities catch up with him.

Probable Cause

The term “probable cause” refers to a legitimate belief that a person has committed a crime or will commit a crime in the future. For a police officer to have probable cause, he must possess enough information about the situation to support his belief that the person he suspects is actually committing, or will commit, a crime. It is not enough to simply suspect someone of a crime. For probable cause to exist, the officer must have factual proof.

Courts rely on probable cause to determine whether a defendant committed a crime. To do this, they measure whether an average person with a reasonable level of intelligence would believe that the evidence provided is enough to prove that the defendant is guilty of the charges against him. The ways in which an individual can come to such a conclusion include:

  • By observing the situation first-hand
  • Through information provided by witnesses and informants
  • Through sensory perception (sight, hearing, etc.)
  • By using his expert knowledge to evaluate the facts at hand

Fruit of the Poisonous Tree

The phrase “fruit of the poisonous tree” refers, in the legal sense, to evidence the police obtain illegally, and then try to use against a defendant to build their case. For example, 4th Amendment examples of violations may include officers coercing, or forcing, a suspect to confess to a crime he did not commit, simply to stop the officers from grilling him for hours on end. The phrase “fruit of the poisonous tree” can refer to any evidence the police obtain illegally, including through illegal wiretaps or after arresting someone without a warrant.

Inevitable Discovery

There are exceptions to the fruit of the poisonous tree rule, and these exceptions have a name: “inevitable discovery.” Inevitable discovery refers to evidence the police obtained illegally but that the prosecution can still use to strengthen their case.

In these cases, the court determines the police could have found the information legally, given enough time, even if they initially came upon the information illegally. Therefore, this evidence becomes “inevitable” discovery because it is “inevitable” that the police would have found it anyway, even if they had done so legally, which is why courts may permit its use.

4th Amendment Example Involving a Potential Jewelry Store Robbery

An example of a 4th Amendment violation occurred in Terry v. Ohio (1968). Here, a police officer noticed a group of men, one of which was John Terry, loitering in front of a jewelry store. This caused him to suspect they were “casing the joint” with the intent of robbing the store. He approached the men, told them he was a police officer, and frisked them. During the frisk, the officer found illegal, concealed weapons. He arrested the men, and after their trial, the court found them guilty. Terry received a sentence of three years in prison on the charge of illegal carrying a concealed weapon.


The defendant appealed the case all the way up to the U.S. Supreme Court. Unfortunately for him, however, the Court ultimately sided with the lower court. The Court held that an officer may pat down a suspect to look for weapons if he has reasonable grounds for suspecting that individual of possessing a weapon. According to the Court, the officer conducted a reasonable search with probable cause.

Said the Court:

“We conclude that the revolver seized from Terry was properly admitted in evidence against him. At the time he seized petitioner and searched him for weapons, Officer McFadden had reasonable grounds to believe that petitioner was armed and dangerous, and it was necessary for the protection of himself and others to take swift measures to discover the true facts and neutralize the threat of harm if it materialized. The policeman carefully restricted his search to what was appropriate to the discovery of the particular items which he sought.

Each case of this sort will, of course, have to be decided on its own facts. We merely hold today that, where a police officer observes unusual conduct which leads him reasonably to conclude in light of his experience that criminal activity may be afoot and that the persons with whom he is dealing may be armed and presently dangerous, where, in the course of investigating this behavior, he identifies himself as a policeman and makes reasonable inquiries, and where nothing in the initial stages of the encounter serves to dispel his reasonable fear for his own or others’ safety, he is entitled for the protection of himself and others in the area to conduct a carefully limited search of the outer clothing of such persons in an attempt to discover weapons which might be used to assault him. Such a search is a reasonable search under the Fourth Amendment, and any weapons seized may properly be introduced in evidence against the person from whom they were taken.”

Related Legal Terms and Issues

  • Defendant – A party against whom a person has filed a lawsuit in civil court, or who stands accused of, or charged with, a crime or offense.
  • Trial – A formal presentation of evidence before a judge and jury for the purpose of determining guilt or innocence in a criminal case, or to rule in a civil matter.
  • Warrant – A writ issued by a court or other legal official authorizing law enforcement or other agency to make an arrest, search a premises, or take some other action related to the administration of justice.