The Fourth Amendment to the United States Constitution embodies the fundamental values of natural rights and personal liberty in terms of ownership and property. Specifically, it defends the security of citizens in their “persons, houses, papers, and effects.” It further restrains government intrusion into the private lives of Americans.

Warrants are therefore the prime protection of the Fourth Amendment against government incursion. For example, in Mapp v Ohio  1961, police obtained evidence without a legal warrant, and the Supreme Court declared that evidence obtained in violations of the Fourth Amendment may not be used in trial. This case brought the exclusionary rule, which prevents illegally obtained evidence from being used in trial and helps hold law enforcement accountable.

But today, most Fourth Amendment issues involve technology. After all, search and seizure methods have advanced far further than our Founding Fathers expected. Beginning in 1928, Olmstead v. United States  ruled wiretapping private telephone conversations without a warrant is permitted and neither a Fourth nor Fifth Amendment violation. 

However, as technology became prominent in everyday life, Katz v. United States  in 1967 would overturn the decision. Katz used a public pay phone to send illegal gambling wagers, unaware the FBI was recording him. The Supreme Court held, “certain details, such as shutting the door on the telephone booth, help determine if a person intends for a conversation to be private.” This lead to the creation of the “reasonable expectation” test. 

In other words, if the individual shows his affairs are meant to be private, and society is willing to recognize it, privacy is guaranteed.

When it comes to national security, though, the government will often prioritize it. In fact, the balance between security and liberty has always been a concern. In Smith v. Maryland, the Supreme Court held a pen register, a device used to record the numbers dialed, without a warrant is not a search violation. People voluntarily provide their numerical information to telephone companies, and therefore surrender their privacy to these businesses. As a result, Smith did not have a reasonable expectation of privacy to those numbers.

The 1979 case established the third party doctrine that declares anyone who hands over their information to third parties like banks and phone companies abandon privacy. So police could ask third parties for information especially if it’s a matter of security. Fortunately, the case of Riley v. California  in 2014, protects our cell phone rights at the very least. It held that the warrantless search of cell phone content during an arrest is unconstitutional.

However, there are exceptions to the Fourth Amendment. First, the stop and frisk rule created in Terry v. Ohio  in 1968. The case allowed officers to check for weapons on a potentially dangerous person with reasonable suspicion, no warrants. The reasonable suspicion would have to be based on “specific and articulate facts” and not simply a hunch to hold officers accountable.

But the most compelling case for a warrantless search would be in times of emergency, or exigent circumstances.

These occur when an officer has probable cause but no time to secure a warrant. For example, when a person’s life is at risk, evidence may be destroyed, or during  a “hot pursuit” of a suspect fleeing.

Other more obvious circumstances do not require warrants. For example, if consent is given. Or if the evidence is in plain sight, it can be seized without approval as cited in Horton v. California  1990. The “search incident to lawful arrest”  is another exception. If a legal arrest is made. Police have the right to search the person and his surrounding area or “wingspan.” In fact, Chimel v. California  1969 emphasizes the need to remove any weapons or dangerous artifacts that could endanger law enforcement.

Perhaps the most common search and seizure though concerns automobiles. Because cars are on public streets, police have a compelling interest to protect the general public from suspicious vehicles. As long as they have probable cause, warrants are not necessary. However, GPS trackers on vehicles are another matter. In 2012, police monitored Jones’s car through a GPS device without a warrant. The court held this is an invasion of privacy because his personal affairs: where he went and what he did was exposed.

Moreover, one issue people have debated for a while now is the good faith doctrine. In 1984, police received a tip identifying Alberto Leon and a few others involved in drug deals. They searched the premises with a warrant. But the warrant was in fact invalid because there was not enough probable cause to have issued it in the first place. Nevertheless, United States v. Leon  decided the police acted in “good faith,” hence the exclusionary rule did not apply. 

Although fourth amendment rights are guaranteed, various exceptions exist. The balance balance security and liberty will always be challenged.