In some cases, individuals may be legally required to file reports that call for information that may be used against them in criminal cases. In United States v Sullivan, the United States Supreme Court ruled that a taxpayer could not invoke the Fifth Amendment's protections as the basis for refusing to file a required federal income tax return. The Court stated: "If the form of return provided called for answers that the defendant was protected from making he could have raised the objection in the return, but could not on that account refuse to make any return at all. We are not called on to decide what, if anything, he might have withheld."
In Garner v United States, the defendant was convicted of crimes involving a conspiracy to "fix" sporting contests and to transmit illegal bets. During the trial the prosecutor introduced, as evidence, the taxpayer's federal income tax returns for various years. In one return the taxpayer had shown his occupation to be "professional gambler." In various returns the taxpayer had reported income from "gambling" or "wagering." The prosecution used this to help contradict the taxpayer's argument that his involvement was innocent. The taxpayer tried unsuccessfully to keep the prosecutor from introducing the tax returns as evidence, arguing that since the taxpayer was legally required to report the illegal income on the returns, he was being compelled to be a witness against himself. The Supreme Court agreed that he was legally required to report the illegal income on the returns, but ruled that the right against self-incrimination still did not apply. The Court stated that "if a witness under compulsion to testify makes disclosures instead of claiming the right, the Government has not 'compelled' him to incriminate himself."
Sullivan and Garner are viewed as standing, in tandem, for the proposition that on a required federal income tax return a taxpayer would probably have to report the amount of the illegal income, but might validly claim the right by labeling the item "Fifth Amendment" (instead of "illegal gambling income," "illegal drug sales," etcetera) The United States Court of Appeals for the Eleventh Circuit has stated: "Although the source of income might be privileged, the amount must be reported." The U.S. Court of Appeals for the Fifth Circuit has stated: "... the amount of a taxpayer's income is not privileged even though the source of income may be, and Fifth Amendment rights can be exercised in compliance with the tax laws 'by simply listing his alleged ill-gotten gains in the space provided for "miscellaneous" income on his tax form'." In another case, the Court of Appeals for the Fifth Circuit stated: "While the source of some of Johnson's income may have been privileged, assuming that the jury believed his uncorroborated testimony that he had illegal dealings in gold in 1970 and 1971, the amount of his income was not privileged and he was required to pay taxes on it." In 1979, the U.S. Court of Appeals for the Tenth Circuit stated: "A careful reading of Sullivan and Garner, therefore, is that the self-incrimination privilege can be employed to protect the taxpayer from revealing the information as to an illegal source of income, but does not protect him from disclosing the amount of his income."
