The Fourth Amendment to the U.S. Constitution protects us from “unreasonable searches and seizures” of our “persons, houses, papers and effects.” It is one of the most important rights we enjoy against government power in this country. It generally requires law enforcement to obtain a search warrant from a neutral judge before conducting a search of a person’s property. This prevents the use of random house-to-house searches for evidence of crime, and other government abuses.
However, the Fourth Amendment’s power is not unlimited. As we will discuss today, there are exceptions to individuals’ right not to be subject to warrantless searches and seizures.
First of all, the Fourth Amendment only applies to government agents. Private investigators, spouses and nosy neighbors are not subject to its provisions, though private people working with law enforcement must follow the amendment. In addition, private people may commit trespassing or break other laws in conducting searches of your home or other property.
Secondly, and more importantly, the Fourth Amendment applies only in situations when the suspect had a reasonable expectation of privacy in the place to be searched or the thing to be seized. Even things in a person’s home or place of business are not reasonably private, the U.S. Supreme Court has ruled, if the person “knowingly exposes them to the public.” On the other hand, objects that the owner tries to keep private, even in a place accessible to the public, may enjoy Fourth Amendment protection.
In many cases, whether a particular set of circumstances called for a search warrant or not must be decided by the court afterward.
When there is a challenge to a search on Fourth Amendment grounds, the party making the challenge in court cannot succeed unless they have “standing.” This means that the person whose rights were allegedly violated must make the challenge. Generally, nobody else can do it on the person’s behalf.
Despite holes in the right against warrantless searches, the Fourth Amendment remains a powerful tool for criminal defendants, who may be able to challenge certain evidence against them as “fruit of the poisonous tree” -- that is, evidence seized during an illegal search. Such evidence is usually not allowed at trial.