The United States Constitution, by the Fifth Amendment, and all state constitutions, provide that no person can be compelled to give evidence against himself, i.e., evidence that would subject himself to criminal prosecution. The purpose of the privilege is to protect a witness from being forced to give testimony leading to the infliction of penalties affixed to the criminal acts upon himself.

This privilege attaches to a witness not only in a criminal proceedings wherein the witness is the defendant, but also attaches to any witness in any judicial proceeding, either civil or criminal. In a civil action, in order to invoke the privilege against self-incrimination, the witness must be faced with a risk of incarceration that is substantial and real, and not merely trifling or imaginary.

See also…

Criminal Law, Arrests, Traffic Tickets