The debate centers on whether police need a warrant to search the cellphones of people they arrest, pitting law enforcement and the federal government against privacy advocates and defense lawyers.
In each of the two cases the justices will address back-to-back Tuesday, criminal defendants were convicted and sentenced to prison partly because police obtained key evidence from their cellphones after a warrantless search.
The Fourth Amendment says that police generally need a warrant before they can conduct a search and that the warrant must be based on "probable cause" evidence that a crime has been committed.
But the Supreme Court has made exceptions when people are arrested, saying 40 years ago that police don't need a warrant to search belongings a suspect is carrying at the time of his or her arrest.
In one of Tuesday's cases, a California state court upheld the conviction of David Leon Riley after San Diego police found evidence on his smartphone that he belonged to a gang and was involved in a gang-related shooting. Prosecutors used video and photographs found on the smartphone to persuade a jury to convict Riley of attempted murder and other charges.
In the other case, from Boston, a federal appeals court said the warrantless search of a cellphone belonging to Brima Wurie violated the Fourth Amendment. After arresting him on suspicion of selling crack cocaine, police examined the call log on his older model "flip phone" and used the information to determine where he lived. When they searched his home after obtaining a warrant, they found crack, marijuana, a gun and ammunition.
Privacy advocates and defense lawyers say that because cellphones potentially contain vast amounts of personal information unrelated to a person's arrest, they should be off limits to a police search without a warrant.
"Beyond the advanced capabilities of the phones themselves, modern cell phones incorporate computers that allow individuals to access the Internet, presenting additional privacy concerns," Riley's attorneys said in a brief to the high court. "Thus, a search incident to arrest could, at the touch of a button, become a search of private and confidential information such as medical records, banking activity and work-related emails."
But the Justice Department says such searches are vital to ensure evidence isn't tampered with or destroyed.
"If an officer does not search an unlocked cellphone as soon as she finds it, a significant risk exists that the police will never be able to recover evidence contained on the phone," said Solicitor General Donald Verrilli in a brief to the court for United States v. Wurie.
Decisions in each case are expected by late June.
Information from the Associated Press was used in this article.