"Search and Seizure" and the Fourth Amendment

The Fourth Amendment to the U.S. Constitution protects personal privacy, and every citizen's right to be free from unreasonable government intrusion into their persons, homes, businesses, and property -- whether through police stops of citizens on the street, arrests, or searches of homes and businesses. Lawmakers and the courts have put in place legal safeguards to ensure that law enforcement officers interfere with individuals' Fourth Amendment rights only under limited circumstances, and through specific methods.
What Does the Fourth Amendment Protect?
In the criminal law realm, Fourth Amendment "search and seizure" protections extend to:
A law enforcement officer's physical apprehension or "seizure" of a person, by way of a stop or arrest; and
Police searches of places and items in which an individual has a legitimate expectation of privacy -- his or her person, clothing, purse, luggage, vehicle, house, apartment, hotel room, and place of business, to name a few examples.
The Fourth Amendment provides safeguards to individuals during searches and detentions, and prevents unlawfully seized items from being used as evidence in criminal cases. The degree of protection available in a particular case depends on the nature of the detention or arrest, the characteristics of the place searched, and the circumstances under which the search takes place.
When Does the Fourth Amendment Apply?
The legal standards derived from the Fourth Amendment provide constitutional protection to individuals in the following situations, among others:
An individual is stopped for police questioning while walking down the street.
An individual is pulled over for a minor traffic infraction, and the police officer searches the vehicle's trunk.
An individual is arrested.
Police officers enter an individual's house to place him or her under arrest.
Police officers enter an individual's apartment to search for evidence of crime.
Police officers enter a corporation's place of business to search for evidence of crime.
Police officers confiscate an individual's vehicle or personal property and place it under police control.
"Search and Seizure" and the Fourth Amendment
Potential scenarios implicating the Fourth Amendment, and law enforcement's legal obligation to protect Fourth Amendment rights in those scenarios, are too numerous to cover here. However, in most instances a police officer may not search or seize an individual or his or her property unless the officer has:
A valid search warrant;
A valid arrest warrant; or
A belief rising to the level of "probable cause" that an individual has committed a crime.
What if My Fourth Amendment Rights Are Violated?
When law enforcement officers violate an individual's constitutional rights under the Fourth Amendment, and a search or seizure is deemed unlawful, any evidence derived from that search or seizure will almost certainly be kept out of any criminal case against the person whose rights were violated. For example:
An arrest is found to violate the Fourth Amendment because it was not supported by probable cause or a valid warrant. Any evidence obtained through that unlawful arrest, such as a confession, will be kept out of the case.
A police search of a home is conducted in violation of the homeowner's Fourth Amendment rights, because no search warrant was issued and no special circumstances justified the search. Any evidence obtained as a result of that search cannot be used against the homeowner in a criminal case.