See also: Fifth Circuit says law enforcement doesn’t need warrants to search phones at the border https://monero.town/post/402125
Seems like a 4th amendment issue. Can you compel me to unlock a filing cabinet? To hand over a journal? To allow you to read my mail? With a warrant that covers those items? Sure. But without a warrant that’s gonna be a no. Any ruling which would treat a phone differently is blatantly ignoring the constitution.
You may be absolutely right about a warrantless search discussed in the “See also”. EFF’s opinion (the main link) is about something different, though somewhat related. The situation seems to be…
Police procured a search warrant for defendant’s cell phone but were unable to execute the warrant because the cell phone was passcode protected and defendant refused to provide the passcode. Accordingly, the State filed a motion to compel production of the cell phone’s passcode.
EFF argues that even in this situation with a warrant, Fifth Amendment protections against self-incrimination mean that the defendant can’t be forced to reveal the passcode:
“When the government demands someone turn over or enter their passcode, it is forcing that person to disclose the contents of their mind and provide a link in a chain of possibly incriminating evidence,” said EFF Surveillance Litigation Director Andrew Crocker. “Whenever the government calls on someone to use memorized information to aid in their own prosecution—whether it be a cellphone passcode, a combination to a safe, or even their birthdate—the Fifth Amendment applies.”