In a 9-0 verdict, the justices found that fourth amendment protections against unlawful search and seizure extend to cellular phones, comparing the devices to homes in the extent of personal and private information found within them.
"Modern cell phones are not just another technological convenience. With all they contain and all they may reveal, they hold for many Americans “the privacies of life.," reads the unanimous opinion. "The fact that technology now allows an individual to carry such information in his hand does not make the information any less worthy of the protection for which the Founders fought. Our answer to the question of what police must do before searching a cell phone seized incident to an arrest is accordingly simple— get a warrant."
The justices determined that cellphones aren't just phones:
"Cell phones differ in both a quantitative and a qualitative sense from other objects that might be kept on an arrestee’s person. The term “cell phone” is itself misleading shorthand; many of these devices are in fact minicomputers that also happen to have the capacity to be used as a telephone. They could just as easily be called cameras, video players, rolodexes, cale ndars, tape recorders, libraries, diaries, albums, televisions, maps, or newspapers. "
The "immense storage capacity" of modern mobile gadgets put them beyond the scope of normal objects found on a person during a search--and into the realm protected by the fourth amendment.
"Not every search 'is acceptable solely because a person is in custody.' To the contrary, when “privacy-related concerns are weighty enough” a “search may require a warrant, notwithstanding the diminished expectations of privacy of the arrestee.” ... One such example, of course, is Chimel . Chimel refused to “characteriz[e] the invasion of privacy that results from a top-to-bottom search of a man’s house as ‘minor.’ ... Because a search of the arrestee’s entire house was a substantial invasion beyond the arrest itself, the Court concluded that a warrant was required."
On the claim that failing to do quickly so allowed suspects to remote-wipe evidence.
"We have also been given little reason to believe that either problem is prevalent. The briefing reveals only a couple of anecdotal examples of remote wiping triggered by an arrest. ... imilarly, the opportuni ties for officers to search a password-protected phone before data becomes encrypted are quite limited. Law enforcement officers are very unlikely to come upon such a phone in an unlocked state because most phones lock at the touch of a button or, as a default, after some very short period of inactivity. ... in situations in which an arrest might trigger a remote-wipe attempt or an officer discovers an unlocked phone, it is not clear that the ability to conduct a warrant - less search would make much of a difference. "
Wonderfully, the justices suggest that if officers are really concerned about this sort of thing, they should take the phone into evidence, turn it off, remove the battery, and put it in a miniature faraday cages, "essentially sandwich bags made of aluminum foil: cheap, light weight, and easy to use. "
On the notion that Cops needs to search phones to protect themselves:
"Digital data stored on a cell phone cannot itself be used as a weapon to harm an arresting officer or to effectuate the arrestee’s escape. ... data on the phone can endanger no-one."
It's not that law enforcement can't search phones -- they just need a warrant.
We cannot deny that our decision today will have an impact on the ability of law en forcement to combat crime. Cell phones have become important tools in facilitating coordination and communication among members of criminal enterprises, and can provide valuable incriminating information about dangerous criminals. Privacy comes at a cost. Our holding, of course, is not that the information on a cell phone is immune from search; it is instead that a warrant is generally required before such a search, even when a cell phone is seized incident to arrest.
And even then, some warrantless searches remain justifiable:
Such exigencies could include the need to prevent the imminent destruction of evidence in individual cases, to pursue a fleeing suspect, and to assist persons who are seriously injured or are threatened with imminent injury.