What Friday's SCOTUS ruling means for you and your cell phone

DURHAM, NC (WTVD) -- The Supreme Court of the United States issued a landmark ruling on Friday mandating that law enforcement should generally obtain search warrants before reviewing location and mapping data on a user's smartphone.

The court's decision followed arguments brought by plaintiff Timothy Carpenter, who was convicted of multiple robbery and gun offenses in 2010. With the help of the American Civil Liberties Union (ACLU), Carpenter sued and challenged the conviction, arguing investigators violated his privacy because investigators didn't get a warrant for his cell phone records.

The government countered that argument that police don't need a warrant to get cell phone records because the data is collected by a third party.

In a narrow 5-4 decision, Chief Justice John Roberts joined four liberal justices and declared that "individuals have a reasonable expectation of privacy in the whole of their physical movements," and noted that a phone's GPS records "give the Government near-perfect surveillance and allow it to travel back in time to retrace a person's whereabouts."

The majority opinion also cited the Fourth Amendment, which prohibits "unreasonable searches and seizures."

Marcus Hill, a criminal defense attorney of more than 20 years, told ABC11 the SCOTUS decision goes to the core of the American criminal justice system.

"This is the basis of our system- which is you're presumed innocent until proven guilty," Hill said. "What's happened is our lives are much more intertwined around cell phones today. They have so much sensitive and personal data about you, your family and your friends."

Kate Shaw, a law professor and Supreme Court expert, told ABC News Friday's decision is consistent with previous cases about the Fourth Amendment and how it applies to the digital age.

"Here, the Court explains that shifts in technology require revisiting what's known as the "third party doctrine," the idea that if you've knowingly shared information with a third party, you have a reduced expectation of privacy in that information," Shaw explained. "The government argued that by 'sharing' information about his location with his cell phone company, the defendant had lost any expectation of privacy, but the Court rejects that argument, finding that the defendant had a reasonable expectation of privacy and that a warrant was required to access information about his location derived from cell towers."

ABC News also reported that tech giants like Apple and Facebook sided with Carpenter and argued that because the data transmitted by electronic devices "can reveal a wealth of detail about people's personal lives."

In Hill's perspective, though, the ruling does not answer all outstanding questions about cell phones and the expectation of privacy.

"The question is can they force you to provide your passcode or can they force the cell phone to provide passcode so they can search the cell phone."

The decision is also not a blanket requirement for a search warrant; Chief Justice Roberts leaves open the door for warrantless searches in cases of "bomb threats, active shootings, and child abductions."