The Fourth Amendment protects every American from “unreasonable search and seizure.” This amendment is central to the criminal justice system.

To protect the rights of the people and avoid unreasonable searches and seizures, law enforcement is typically required to get a warrant, a document issued by a court that allows the police to perform a search or seizure. And in order to get a warrant, the police must show probable cause that evidence of a crime will be found.

However, the warrant requirement does have limitations and exceptions, including exigent circumstances (the police have no time to get a warrant) and plain view (the evidence is in plain sight). Another exception occurs during an arrest: when a police officer arrests an individual, he or she can perform a search of the person.

The arrest exception to the warrant requirement was enacted primarily to protect police officers and prevent the destruction of evidence. This exception, historically, has applied to whatever a person was carrying, including his or her wallet purse, address book, and diary.

The Supreme Court recently ruled, however, that the arrest exception does not apply to a person’s cell phone.

The court heard two cases that involved the warrantless cell phone searches of two men. In both cases, law enforcement’s search of the cell phones led to the convictions of the two men.

Lawyers for the Justice Department argued that cell phones should be treated the same as a wallet, purse, or address book. They also asserted that, if police were not permitted to search the cell phones during the arrest, data from the cell phone could be lost—and evidence destroyed—through a “remote wiping” program.

The Supreme Court justices didn’t buy either of these arguments.

Chief Justice Robert said that comparing cell phones to wallets “is like saying a ride on horseback is materially indistinguishable from a flight to the moon.”

The justices stated that cell phones searches require a warrant due to the enormous amount of information on a cell phone. Cell phones are used by more than 90 percent of Americans, and the majority of Americans have smartphones—which show not only a record of calls and texts but also a person’s photos, emails, videos, contact list, calendars, and more. Cell phone GPS data can show where a person has been. Even more personal information could be found in a person’s Internet history.

Without a warrant, police could have unfettered access to the most private details of a person’s life.

The justices also stated that the possibility that cell phone data could be destroyed if the police could not immediately perform a search was remote and was already addressed under the exigent circumstances exception. If police are concerned that a cell phone’s information could be erased, the justices said, they can turn off the phone, remove its battery, or place it in an aluminum bag.

This ruling by the Supreme Court was a clear victory for privacy advocates and for the rights of every American.

It is, of course, important that law enforcement is able to do its job—but a person’s Fourth Amendment rights should not be abandoned in the process.