The 4th Amendment protects people's and businesses' freedom from unreasonable searches, seizures, and other intrusions by the government. In other words, people have the right to be free from unreasonable inspections (searches) and confiscations (seizures) by a government or by people authorized by that government. The amendment does not guarantee complete protection from all searches and seizures, but it covers those that courts consider unreasonable. Whether or not a search or seizure is unreasonable hinges on the understanding of an expectation of privacy.
This expectation of privacy test was developed in Katz v. United States Supreme Court (1967), one of the essential cases for 4th Amendment analysis. The test is based on whether the individual or claimant had an expectation of privacy according to public norms. It has two parts: the individual must show an actual (subjective) expectation of privacy, and society as a whole must recognize that expectation as reasonable. Both test parts must be met to prove the government's actions violated the individual's or business's 4th Amendment rights.
After reviewing and interpreting Katz and other cases claiming unreasonable searches and seizures, the Supreme Court changed its standard on this issue. The initial standard was that a person had to prove that they had been subject to an invasion of privacy. In contrast, the evolving standard has become the expectation of privacy. However, it is up to the business or person who endured the search or seizure to prove that the government's search was an invasion of privacy.
A search warrant is a legal document that allows police, state actors, and the government to enter and search premises. However, warrantless searches and seizures of properties are not necessarily illegal. Courts have allowed searches or seizures of some properties that were in plain view, abandoned, or in an open field. Courts call this the plain view exception.
The courts want police, state actors, and the government to get a search warrant before making a search or seizing property. However, sometimes this is not possible because there is an emergency or because a suspect may try to escape or destroy evidence. Courts refer to this as exigent circumstances.
State laws can establish higher standards for protection, but they cannot lower the standard that the 4th Amendment imposes. Under the exclusionary rule, courts exclude any evidence found as a result of a 4th Amendment violation, with some exceptions. There are six primary exceptions: (1) search incident to a lawful arrest (if someone is lawfully arrested, the authorities have the right to search the person and the surrounding area to ensure no evidence is destroyed and that the arresting officers are not facing safety issues); (2) plain view (if police officers are legally present and witness, in plain view, an illegal substance or property, they are allowed to use that information in the arrest and report); (3) consent (if the person agrees to the search, then it is permissible); (4) stop and frisk (if an officer has a reasonable suspicion of any criminal act, they may stop the person, and if the officer fears for safety or has a reason to believe the person is armed, then the officer may search the person); (5) automobile exception (because automobiles [and boats] are so mobile, an officer can search them with sufficient probable cause); and (6) exigent or emergency circumstances (this usually occurs when police officers are in pursuit of someone; they can enter property without a warrant because of the exigent circumstances).
When evidence is obtained illegally and not in accordance with the 4th Amendment or these exceptions, then it is considered tainted. That means the evidence cannot be used, and this is often referred to as fruit of the poisonous tree. If the search is not legal or valid, then any evidence obtained later as a result is suppressed or thrown out.
The 4th Amendment usually applies to criminal proceedings, but it can affect the workplace as well. Before business leaders conduct drug tests, perform credit checks, or search employees' desks or computers, they must know employees' rights under the 4th Amendment. It is important for companies to understand that public-sector workers have slightly more protection against workplace searches than private-sector workers do. This is because the conduct of their employers is deemed to be a "state action" and is subject to the Bill of Rights. For this reason, public employees are protected by the 4th Amendment of the U.S. Constitution from unreasonable search and seizure, defined as inspections and confiscations by the U.S. government or state actors. The Constitution only applies to "state action," which applies to public employees, not private employees.