McCulloch v. Maryland established that Congress has implied powers under the Necessary and Proper Clause to pursue its enumerated goals using any means that are rationally related to those goals. Chief Justice John Marshall ruled that "necessary" means convenient and useful, not indispensable. The decision also held that states cannot tax or interfere with valid federal institutions because the Constitution's Supremacy Clause makes federal law supreme. This case gave the national government broad discretion to choose how to exercise its powers and established the principle that federal authority outweighs conflicting state actions.

McCulloch v. Maryland established that Congress has implied powers under the Necessary and Proper Clause to pursue its enumerated goals using any means that are rationally related to those goals. Chief Justice John Marshall ruled that "necessary" means convenient and useful, not indispensable. The decision also held that states cannot tax or interfere with valid federal institutions because the Constitution's Supremacy Clause makes federal law supreme. This case gave the national government broad discretion to choose how to exercise its powers and established the principle that federal authority outweighs conflicting state actions.