In the United States v. Cors case of 1948, the Supreme Court ruled on a dispute involving federal income tax law. The respondent, Cors, had received money from his mother's estate in 1939 and again in 1940 but did not include these amounts as gross income on his federal income tax returns for those years. The Commissioner of Internal Revenue determined that these were taxable gifts under Section 22(b)(3) of the Internal Revenue Code and assessed deficiencies against him accordingly. However, Cors argued that they were non-taxable gifts because he was entitled to them under state law due to an agreement made with his siblings after their mother’s death. The Supreme Court held that even though there might have been an enforceable agreement between the siblings regarding division of their mother's estate according to her wishes expressed outside her will (which would make it seem like a gift), this does not change its character as "income" within meaning of Sixteenth Amendment or exempt it from taxation under Section 22(b)(3). Therefore, such funds are subject to federal income tax.

In the dissenting opinion for United States v. Cors, it was argued that the majority's ruling contradicted previous decisions regarding tax evasion cases and set a dangerous precedent. The dissenting justices believed that the defendant should not be held liable for taxes on income he did not personally receive or control, even if he had an indirect interest in it through his business partnerships. They contended that this interpretation of tax law could lead to double taxation and other unfair practices because partners could potentially be taxed both individually and as part of their partnership. Furthermore, they expressed concern about potential abuse by prosecutors who might use this broad interpretation to target individuals unfairly.