Comment by gck1

They can still make your life very difficult. They could throw you in jail for "obstructing investigation" or something similar.

Not in US, but had my phone seized by authorities and was asked to unlock it. I'm walking free, but I think what really saved me is that I genuinely complied with investigation and the only place where I drew the line was me giving away my password.

If I used my right to remain silent AND not give away the password, I'd probably be charged with something. I'm sure its very similar in many countries, including US.