They dont, amendments exist. Its entirely possible for the states to agree to new rules that will supersede the previous law of the land. They do because they

They dont, amendments exist. Its entirely possible for the states to agree to new rules that will supersede the previous law of the land. They do because they establish basic strictures on the federal government itself. Critically the constitution, and bill of rights, outline what powers are granted to the federal government and which are expressly reserved for the states and citizens. Its the inverse of many (most?) countries that Ive seen. The fed government was granted limited, specific, powers by its constituents. The states and citizens do not derive their rights & powers from the federal government.