In the United States v. United States Coin & Currency case of 1970, the Supreme Court ruled that forfeiture proceedings under Section 7302 of the Internal Revenue Code were punitive in nature and therefore subject to protections provided by the Fifth Amendment. The case arose when $8,674 was seized from a man who had been convicted for not paying taxes on illegal gambling profits. He argued that this seizure constituted double jeopardy as it was an additional punishment after his criminal conviction. The government contended these were remedial forfeitures aimed at compensating for tax evasion rather than punishing it; hence they did not violate constitutional rights against double jeopardy or self-incrimination. However, Justice Thurgood Marshall wrote in his majority opinion that such forfeitures are indeed penalties since their primary purpose is deterrence and retribution rather than compensation for loss or reimbursement of costs incurred by the government due to unlawful conduct.

In the dissenting opinion for United States v. United States Coin & Currency, Justice Harlan argued that forfeiture laws should not be applied in cases where they would effectively serve as a second punishment for the same offense. He believed this to be a violation of the Double Jeopardy Clause of the Fifth Amendment, which prohibits multiple punishments for one offense. In his view, when an individual has already been criminally prosecuted and punished by fine or imprisonment, it is unjust to then seize their property under forfeiture laws related to that same crime. This amounts to punishing them twice over - once through criminal proceedings and again through civil procedures - which he saw as unconstitutional double jeopardy.