- Two main clauses in the U.S. Constitution make state laws subordinate to federal law: Article I, Section 10 explicitly prohibits any state from making treaties, establishing its own currency, granting titles of nobility, or imposing its own duties on imports. Article VI, Section 2 affirms federal law as "the supreme law of the land," by which "the judges in every state shall be bound..., any thing in the Constitution or laws of any state to the contrary notwithstanding." Both of these clauses are involved in some arguments over Arizona's 2010 passage of SB1070, an attempt to further enforce, at the state level, federal immigration policies.
- The U.S. Code has included Title 42, Section 1983 since 1871, and it was later incorporated into the Civil Rights Act. Officials of the states may not, "under color" of state authority, deprive anyone of constitutional rights. Anyone who does is subject to legal "proceeding[s] for redress." A Section 1983 complaint may be brought in either state or federal court, and a plaintiff can receive only actual damages. The Justice Department's Civil Rights Division includes on its website selected recent cases of official misconduct, with the U.S. as plaintiff, that range from a Border Patrol officer who served 366 days in prison for pistol-whipping a suspected illegal immigrant and threatening to kill another to a Los Angeles police officer sentenced to 102 years for participation in a home-invasion ring and firearms violations.
- When the federal courts, especially the Supreme Court, rule on major constitutional issues, they establish precedents that may change the constitutional status of existing state laws and open states to complaints. A well-known example is the 1954 ruling, 347 U.S. 483, known as Brown v. Board of Education, which found unconstitutional racial segregation of public schools. Straightforward as it may seem, implementing integration is anything but easy. As recently as 1995 the Supreme Court ruled on a case, Missouri v. Jenkins, itself in litigation for 18 years, by a divided vote of 5 to 4.
- Because the federal government, and not the states, conducts foreign policy, there have been occasions when commitments made by the nation must apparently be enforced against the interests of a state, such as in a criminal proceeding. For instance, in 2007, Solicitor General Paul Clement filed a Supreme Court brief arguing that the decision of a Texas appellate court upholding the death sentence of a Mexican national convicted of gang rape should be reversed. Clement's argument was based on the failure of Texas to notify a Mexican consulate that it was prosecuting this citizen, which might have afforded him assistance. The argument cited decisions of the International Court of Justice and a treaty ratified by the U.S. in 1969. The Supreme Court nevertheless upheld the appellate decision. A dissenting opinion cited the supremacy clause.