The Gregg v. United States case in 1968 revolved around the issue of whether or not a taxpayer's failure to keep adequate records and cooperate with tax investigators could be used as evidence against him in a criminal tax evasion trial. The defendant, Mr. Gregg, was charged with willfully attempting to evade income taxes for three years by underreporting his income from illegal gambling activities. During the investigation process, he failed to provide sufficient records and did not fully cooperate with IRS agents which led them to reconstruct his net worth using indirect methods. In court, this lack of cooperation was presented as evidence of guilt which resulted in conviction on all counts. However, upon appeal at the Supreme Court level it was ruled that such behavior cannot be considered substantive evidence of guilt but can only serve as corroborative proof when there is already direct independent evidence pointing towards fraudulence or wrongdoing. Therefore while affirming Gregg’s conviction due its reliance on substantial other evidences proving fraudulent intent beyond reasonable doubt; it also clarified that non-cooperation alone does not establish guilt thereby setting an important precedent for future cases involving similar circumstances.

In the dissenting opinion for Gregg v. United States, Justice Thurgood Marshall argued that the majority's decision to uphold Gregg's conviction was flawed due to a misinterpretation of the federal bank robbery statute. He contended that this law should not be applied in cases where no actual threat or force is used during a theft. In his view, merely passing a note to a teller demanding money does not constitute "force and violence" or "intimidation," as specified by the statute. Furthermore, he believed that interpreting it otherwise would blur important distinctions between different degrees of criminal behavior and could lead to disproportionately severe punishments for less serious offenses.