> Courts at the state and federal level, including the U.S. Supreme Court, repeatedly have rejected the theory of nullification.[2] The courts have decided that

> Courts at the state and federal level, including the U.S. Supreme Court, repeatedly have rejected the theory of nullification.[2] The courts have decided that under the Supremacy Clause of the Constitution, federal law is superior to state law, and that under Article III of the Constitution, the federal judiciary has the final power to interpret the Constitution. Therefore, the power to make final decisions about the constitutionality of federal laws lies with the federal courts, not the states, and the states do not have the power to nullify federal laws. > Between 1798 and the beginning of the Civil War in 1861, several states threatened or attempted nullification of various federal laws. None of these efforts were legally upheld. The Kentucky and Virginia Resolutions were rejected by the other states. The Supreme Court rejected nullification attempts in a series of decisions in the 19th century, including Ableman v. Booth, which rejected Wisconsin's attempt to nullify the Fugitive Slave Act. The Civil War ended most nullification efforts. > In the 1950s, southern states attempted to use nullification and interposition to prevent integration of their schools. These attempts failed when the Supreme Court again rejected nullification in Cooper v. Aaron, explicitly holding that the states may not nullify federal law. I wouldn't say they absolutely can since every attempt to do this so far has failed in the courts. It seems like a pretty flimsy theory since the Constitution explicitly says otherwise.