Anyone who watches crime dramas on television is familiar with the scene where police officers enter a home or business brandishing a search warrant. The Fourth Amendment to the United States Constitution guarantees the people's right to be free from unreasonable searches and seizures, which often -- but not always -- means that government agents must have a warrant to search and seize your person and property.
The Fourth Amendment
Here is the full text of the Fourth Amendment:
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 the people from unreasonable searches and seizures, which means that many searches are fine as long as they meet certain requirements. Searches are generally considered reasonable when: 1) a judge issues a search warrant based on probable cause; or 2) certain situations occur that justify a search without a warrant (a search for weapons after an arrest, for example).
When the Fourth Amendment Doesn't Apply
The Fourth Amendment's requirements don't apply when a person doesn't have a "legitimate expectation of privacy" in the place or thing searched. If there isn't an expectation of privacy, then the Fourth Amendment doesn't come into play, and officers conducting a search don't have to meet its requirements.
The United States Supreme Court created a test for determining when a legitimate expectation of privacy exists. The test has two parts:
An example might help clarify the point: most people feel that their homes are private, so there is a subjective expectation of privacy in one's home. Most people in society would find this expectation reasonable, so a police search of one's home must satisfy the Fourth Amendment's reasonableness requirement.
If someone leaves evidence of a crime on their front lawn, however, it's likely that a police seizure of that evidence would not constitute an unreasonable search since most people in a society would not expect that an object that was clearly visible to anyone passing by would remain private. Even if the owner of the home or the evidence genuinely expected that the area would remain private, that expectation would not be reasonable, and so the seizure would not have to meet the requirements of the Fourth Amendment.
Who Does the Fourth Amendment Apply To?
Also keep in mind that the Fourth Amendment's requirements only apply to government actors. Private individuals, including security guards, don't fall under the Fourth Amendment's restrictions. While a private individual may break other laws if they conduct a search of a person or their belongings, any evidence they discover in the process would still be admissible in court.
If a government actor conducts an illegal search (one that violates the Fourth Amendment), the government cannot present any evidence discovered during that search at trial. Known as the "exclusionary rule," this rule aims to deter police officers from conducting unreasonable searches. Opponents of the exclusionary rule, however, argue that it lets guilty criminals go free on technicalities.
The Exclusionary Rule
In addition, evidence obtained through illegal searches cannot lead police to the discovery of other evidence. This legal rule, known as the "fruit of the poisonous tree," is also designed to prevent government actors from invading people's privacy by conducting unreasonable searches. If police know, so the theory goes, that any evidence they obtain based on what they discover in an illegal search will be thrown out, they won't conduct illegal searches in the first place.
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 walks into Chris' house and finds drugs and a scale on the kitchen table. Officer Joe arrests Chris, but the judge throws out the evidence of the drugs and scale on the basis of the exclusionary rule.
In the example above, instead of finding drugs and a scale, Office Joe finds a map to locations throughout the city where Chris is storing his drugs for sale. Officer Joe collects the drugs and enters both them and the map as evidence. The map is thrown out because of the exclusionary rule, and, because Officer Joe would not have discovered the drugs without the map, the fruit of the poisonous tree doctrine prevents the use of the drugs as evidence.
It is important to note, however, that just because the prosecution can't use certain evidence at trial, it doesn't mean that a judge will dismiss a case or that a jury will acquit the defendant. Prosecutors may have enough other evidence to convict the defendant even without the results of the illegal search.
Plus, while prosecutors can't use improperly obtained evidence to secure a conviction, that evidence may enter into other areas of the trial. For instance:
Learn More About Search Warrants: Talk to an Attorney
Evidence issues arise in nearly every kind of case, but the rules of evidence are complicated and sometimes depend on local laws. Understanding your rights and the rules of procedure are critical to successfully navigating the court system. If you have questions about pending or possible criminal charges against you or a loved one, consider speaking with a qualified criminal attorney to begin developing a defense strategy.