The Fourth Amendment of the Constitution protects you against unreasonable searches and seizures of your property. This means that law enforcement typically must obtain a warrant in order to conduct a search of your person or premises.

However, in the eyes of the law there are situations in which reasonability dictates that it is not necessary to obtain a warrant before conducting a search.

  1. Exigent circumstances

In an emergency situation, where there is a possibility of someone becoming hurt or killed, law enforcement need not obtain a warrant to enter a building and conduct a search. However, the officers must be able to testify to the presence of emergency circumstances in court.

  1. Traffic stops

The Fourth Amendment allows authorities to conduct a search of your car’s interior without a warrant after pulling you over for a reasonable and articulable suspicion of a traffic law violation. For example, if your car was weaving in and out of your lane, a law enforcement officer may suspect you of impairment and pull you over. Thereupon, the officer would have the right to search your car’s interior from the backseat to the glove compartment without a warrant. However, the officer would need probable cause to check your trunk during a traffic stop.

  1. Terry stops

The Supreme Court case Terry v. Ohio established that a law enforcement officer may stop any person believed to be participating in criminal activity in a public place. To protect the officer from hidden weapons, he or she may conduct a search of the individual’s outer clothing. However, these types of searches, called Terry frisks or Terry stops, are limited in that the officer can only confiscate objects that feel like weapons.

  1. Good faith

Sometimes authorities may act on a search warrant that later turns out to be invalid. However, if the law enforcement officers conducted a search acting on a good-faith belief that the warrant was legitimate, the search is still reasonable in the eyes of the law. On the other hand, if willful deception by authorities is the reason for the warrant’s invalidity, the search is no longer reasonable.

It is also important to understand that the Fourth Amendment only applies to law enforcement officers employed by a government entity. It does not apply to private citizens, such as security personnel for hire.