The 5th amendment and the Miranda warning are designed to protect the constitutional rights of individuals in the U.S. by preventing coercive interrogations and abuse of government authority.
Miranda warnings take their name from the Miranda v. Arizona case, in which the Supreme Court held that an elicited incriminating statement by a suspect will not constitute admissible evidence unless the suspect was informed of the right to decline to make self-incriminatory statements and the right to legal counsel (hence the so-called "Miranda rights"), and makes a knowing, intelligent and voluntary waiver of those rights.
Therefore, Miranda warnings are an extension of 5th amendment rights. i.e. the warnings are issued by police to inform the suspect of their fifth amendment rights and to ensure that the suspect knows these rights and, if he or she chooses to waive these rights, they do it voluntarily and knowing full well the consequences of their actions.
The most well-known provision of the fifth amendment is the right against self-incrimination. In other words, you do not have to talk to the police or testify in a trial if your testimony is evidence that you committed a crime.
The text of the fifth amendment is as follows:
No person shall be held to answer for a capital, or otherwise infamous crime, unless on a presentment or indictment of a Grand Jury, except in cases arising in the land or naval forces, or in the Militia, when in actual service in time of War or public danger; nor shall any person be subject for the same offense to be twice put in jeopardy of life or limb; nor shall be compelled in any criminal case to be a witness against himself, nor be deprived of life, liberty, or property, without due process of law; nor shall private property be taken for public use, without just compensation.
The implications are:
- Double jeopardy: Once acquitted, a defendant may not be retried for the same offense.
- Witnesses cannot be forced to incriminate themselves. To "plead the Fifth" means to refuse to answer a question because the response could provide self-incriminating evidence of an illegal act punishable by fines, penalties or forfeiture. Historically, this legal protection was directly related to the use of torture for extracting information and confessions. This protection is granted to witnesses in a trial, suspects in custodial interrogation and defendants on trial.
Certain protections offered by the fifth amendment (e.g. the right to have an attorney present) do not apply to grand juries. However, many states have abolished grand juries and replaced them with preliminary hearings.
Federal income tax
Individuals are required to report all income, including income from illegal activity. They cannot plead the fifth amendment to avoid filing a tax return altogether. They may, however, choose to not describe the exact source of their income by pleading the fifth.
Individuals may be unable to plead the fifth amenment and be forced to testify if the court grants them transactional immunity (immunity from prosecution) or use immunity (a guarantee that their testimony will not be used as evidence against them if they testify).