In Flora v. United States, the Supreme Court ruled that a taxpayer must pay the full amount of an assessed tax before filing a lawsuit to recover it. The case involved William J. Flora who had been assessed with additional income taxes and penalties by the Internal Revenue Service (IRS). He paid part of this assessment but refused to pay the rest, instead suing for a refund on what he had already paid while disputing his liability for the remainder. The IRS argued that under federal law, taxpayers were required to first pay their entire tax bill before they could bring such suits against them in court - known as "full payment rule". In its decision, delivered by Justice Hugo Black, the Supreme Court sided with IRS stating that Congress intended this requirement when it enacted legislation governing lawsuits against government over disputed taxes.

In the dissenting opinion for Flora v. United States, Justice Whittaker argued that the majority's interpretation of "full payment" in Section 1346(a)(1) was incorrect and inconsistent with its historical context. He contended that this section was intended to allow taxpayers to challenge an assessed tax without having to pay it first, as long as they could demonstrate a financial inability or undue hardship caused by paying the full amount upfront. The requirement of full payment before filing suit would effectively deny many taxpayers their day in court due to lack of funds, which he believed contradicted Congress' intent when creating this statute. Furthermore, he pointed out inconsistencies between similar statutes where such a strict interpretation is not applied and criticized the majority for failing to consider these parallels adequately.