McCulloch refers to the landmark Supreme Court case, McCulloch v. Maryland, decided in 1819. This case addressed the balance of power between the federal government and the states. The Supreme Court ruled that the federal government had the authority to create a national bank, affirming the use of implied powers under the Necessary and Proper Clause of the U.S. Constitution. The case also established that states could not tax federal institutions, reinforcing the supremacy of federal law over state law. This decision was significant in shaping the relationship between state and federal powers, influencing future interpretations of the Constitution.