The self-incrimination privilege protects a person from government compulsion to provide a testimonial communication that is incriminating. It applies in criminal cases and can protect answers in other proceedings when they may expose the speaker to prosecution. It does not ordinarily bar collection of physical characteristics such as fingerprints, a voice sample, or a blood sample, because those are not testimonial communications. A defendant also may not be punished at trial for choosing not to testify.

Double jeopardy is a separate protection. After the constitutional protection has attached, government generally may not try a person again for the same offense following an acquittal or conviction, or impose unauthorized multiple punishments for one offense. The result depends on how the first proceeding ended. A hung jury or a conviction reversed for trial error may allow another trial, while an acquittal ordinarily carries special finality. Separate sovereigns can prosecute conduct under their own laws, but one prosecutor cannot evade the clause simply by changing the label on an identical charge.

Due process supplies a broader guarantee of fair government procedure. In a criminal case it supports notice, an opportunity to be heard, and limits on fundamentally unfair official conduct, while specific amendments often provide the more precise rule. Consider a suspect compelled to reveal a safe combination: the testimonial privilege is central. Police taking the safe's physical key presents a different issue. Miranda safeguards custodial interrogation, but the Fifth Amendment privilege is the underlying protection and reaches beyond the police-station setting.

Video lesson: Due Process of Law: Crash Course Government and Politics #28