[NoGravitas]

4th amendment, I think. Regardless, given the current composition of the Court, I wouldn't hold your breath for the situation to improve.

[phpisthebest]

One could make that case, but 4th allows for searches with a warrant

I would say 5th because divulging the contents of ones mind is testimony which one should not be compelled to do, the 5th profits you from being a witness against yourself, reveling a password is being a witness against yourself

[chipsa]

Fifth: the password is testimony. It's searching their things, but the warrant issued by the court means that it's likely a reasonable search (ergo, not a violation of the 4th).