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 Opinion of the Court texting an accomplice who, it is feared, is preparing to detonate a bomb, or a child abductor who may have information about the child's location on his cell phone. The defendants here recognize — indeed, they stress — that such fact- specific threats may justify a warrantless search of cell phone data. See Reply Brief in No. 13-132, at 8-9; Brief for Respondent in No. 13-212, at 30, 41. The critical point is that, unlike the search incident to arrest exception, the exigent circumstances exception requires a court to examine whether an emergency justified a warrantless search in each particular case. See McNeely, supra, at ____ (slip op., at 6).

Our cases have recognized that the Fourth Amendment was the founding generation's response to the reviled "general warrants" and "writs of assistance" of the colonial era, which allowed British officers to rummage through homes in an unrestrained search for evidence of criminal activity. Opposition to such searches was in fact one of the driving forces behind the Revolution itself. In 1761, the patriot James Otis delivered a speech in Boston denouncing the use of writs of assistance. A young John Adams was there, and he would later write that "[e]very man of a crowded audience appeared to me to go away, as I did, ready to take arms against writs of assistance." 10 Works of John Adams 247-248 (C. Adams ed. 1856). According to Adams, Otis's speech was "the first scene of the first act of