聯邦政府有權利義務維護人權

14th amendment

No state shall make or enforce any law which shall abridge the privileges or immunities of citizens of the United States; nor shall any state deprive any person of life, liberty, or property, without due process of law; nor deny to any person within its jurisdiction the equal protection of the laws.

上廁所是不是一個人的life, liberty and property, 可以商酌，但是聯邦政府為了維護個人的life liberty and property而幹涉州法，是有憲法依據的。