The Fourth Amendment is arguably the most important constitutional amendment in the context of criminal cases. It states:
"The right of the people to be secure in their persons, houses, papers, and effects, against unreasonable searches and seizures, shall not be violated."
But what exactly constitutes a search under the Fourth Amendment? Courts have identified two primary categories of searches that trigger Fourth Amendment protections.
What Constitutes a Search?
1. Physical Intrusion (Trespass Doctrine)
The first category of a search is when the government physically intrudes on a person’s private property to obtain information. This means that if law enforcement commits a common-law trespass while gathering evidence, it is considered a search under the Fourth Amendment.
Examples of Physical Intrusions as Searches:
- Entering a home without a warrant.
- Searching a person’s phone or laptop.
- Extracting blood or DNA from an individual.
- Attaching a GPS tracking device to a vehicle (United States v. Jones, 2012).
2. Violation of a Reasonable Expectation of Privacy (Katz Test)
The second category is violating a person’s reasonable expectation of privacy. This principle comes from Katz v. United States (1967), which ruled that a search does not require physical intrusion if law enforcement invades someone’s reasonable expectation of privacy.
Examples of Privacy Violations as Searches:
- Eavesdropping on private conversations (Katz v. United States).
- Using a heat-sensing device to detect home activities (Kyllo v. United States, 2001).
- Tracking a person’s cellphone location without consent (Carpenter v. United States, 2018).
What is NOT Considered a Search?
Certain actions do not fall under Fourth Amendment protections because they do not involve a physical intrusion or violate a reasonable expectation of privacy. These include:
- Abandoned Property – Law enforcement can search trash left at the curb (California v. Greenwood, 1988).
- Items in Plain View – If an officer sees illegal activity in an open space, it is not a search (Horton v. California, 1990).
- Aerial Surveillance – Police can fly over private property and observe activities (Florida v. Riley, 1989).
- Canine Sniffs – A trained dog sniffing luggage at an airport does not constitute a search (Illinois v. Caballes, 2005).
When is a Search Unreasonable?
Under the Fourth Amendment, searches are considered unreasonable unless:
- The government has obtained a valid search warrant supported by probable cause.
- The search falls under a recognized exception to the warrant requirement.
Common Warrant Exceptions
There are several instances where law enforcement can conduct a search without a warrant:
- Consent – If a person voluntarily allows a search.
- Search Incident to Arrest – Police can search a suspect and their immediate surroundings after an arrest (Chimel v. California, 1969).
- Exigent Circumstances – When waiting for a warrant would create a danger or risk of evidence destruction (Kentucky v. King, 2011).
- Automobile Exception – Officers can search a vehicle if they have probable cause to believe it contains evidence of a crime (Carroll v. United States, 1925).
- Plain View Doctrine – If an officer lawfully observes contraband, they can seize it without a warrant.
What Happens if a Search Violates the Fourth Amendment?
If a search is deemed unconstitutional, evidence obtained may be excluded from court proceedings under the Exclusionary Rule (Mapp v. Ohio, 1961). This rule helps prevent unlawful searches by discouraging law enforcement from violating constitutional rights.
Need Legal Help?
If you believe your Fourth Amendment rights were violated, you need an experienced criminal defense attorney.
Contact The Moore Law Firm, PLLC today for a consultation and legal guidance!