I was struck by the Chief Justice’s skepticism of officer safety in Riley, particularly in this paragraph where he faulted the government for offering no evidence to substantiate their concerns.

The United States and California both suggest that a search of cell phone data might help ensure officer safety in more indirect ways, for example by alerting officers that confederates of the arrestee are headed to the scene. There is undoubtedly a strong government interest in warning officers about such possibilities, but neither the United States nor California offers evidence to suggest that their concerns are based on actual experience.

The proposed consideration would also represent a broadening of Chimel’s concern that an arrestee himself might grab a weapon and use it against an officer “to resist arrest or effect his escape.” 395 U. S., at 763. And any such threats from outside the arrest scene do not “lurk[ ] in all custodial arrests.” Chadwick, 433 U. S., at 14–15. Accordingly, the interest in protecting officer safety does not justify dis- pensing with the warrant requirement across the board. To the extent dangers to arresting officers may be impli- cated in a particular way in a particular case, they are better addressed through consideration of case-specific exceptions to the warrant requirement, such as the one for exigent circumstances.

Update: Likewise, the Court was not buying the encryption, or remote wiping argument:

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. See Brief for Association of State Criminal Investigative Agencies et al. as Amici Curiae in No. 13– 132, pp. 9–10; see also Tr. of Oral Arg. in No. 13–132, p. 48. Similarly, the opportunities 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. See, e.g., iPhone User Guide for iOS 7.1 Software 10 (2014) (default lock after about one minute). This may explain why the encryption argument was not made until the merits stage in this Court, and has never been considered by the Courts of Appeals.