"That right also applies to acts that are "testimonial" and have communicative aspects, according to Jennifer Granick, director of civil liberties at the Stanford Center for Internet and Society.
Like giving a password, for example.
"The ultimate question is whether providing a password is testimonial communication," Horowitz said. "In context of a password to a phone, it seems a pretty strong argument that that is" -- and therefore protected by the Fifth Amendment, she said.
However, the government can compel defendants to give up passwords if it's a "foregone conclusion" that prosecutors will find information they already have their hands on, Granick said."