In the 1930 case of Poe v. Seaborn, the United States Supreme Court ruled in favor of Mr. and Mrs. Seaborn, who were residents of Washington State - a community property state where income is considered jointly owned by both spouses regardless of which spouse earned it. The couple had divided their income for federal tax purposes, each claiming half on separate returns to take advantage of lower individual rates rather than filing jointly as married couples typically did at that time under higher joint rates set by federal law. The Internal Revenue Service (IRS) disputed this practice and argued that all income should be attributed to the husband since he was the one who actually earned it. The court held that under Washington's community property laws, each spouse has an immediate vested interest in earnings from either spouse during marriage; therefore they could divide their total combined income equally between them for federal tax purposes despite IRS objections. This decision led Congress to enact new legislation known as "income splitting," allowing all married taxpayers nationwide - not just those living in community property states - to benefit from lower individual rates when filing joint returns.

In the dissenting opinion for Poe v. Seaborn, Justice Butler argued that income should be taxed according to who earned it rather than how property rights are defined under state law. He disagreed with the majority's interpretation of "income" in the Sixteenth Amendment and believed that a person's income should not be divided between spouses simply because they live in a community property state. Instead, he suggested that federal tax laws should apply uniformly across all states regardless of their differing marital property laws. He also expressed concern about potential tax evasion if taxpayers could manipulate their reported incomes by moving to different states or changing their marital statuses. Ultimately, he felt that the court was overstepping its bounds by interpreting federal tax law based on individual state laws instead of applying a consistent national standard.