Final answer:
States cannot make laws that contradict federal laws, as federal law is supreme. This is determined by the Supremacy Clause of the Constitution and is supported by court decisions. State attempts at nullification have been legally ineffective.
Step-by-step explanation:
The Constitution of the United States establishes a system of federalism in which federal law is supreme over state law. This is outlined in the Supremacy Clause of Article VI, which states that the Constitution and federal laws made pursuant to it constitute the 'supreme Law of the Land' and take precedence over any conflicting state laws. The assertion that states could make laws that contradicted federal laws is false. Historically, certain state actions, such as the Virginia and Kentucky Resolutions, did declare that states had the right to nullify federal laws, but these were never legally upheld and are contrary to the principle of federal supremacy.
In practice, states have tried asserting their rights through mechanisms such as interposition or nullification, but these efforts have largely failed when challenged in court. Notably, the Necessary and Proper Clause, which grants Congress the power to make all laws necessary and proper for executing its powers, has not limited the power of the national government; rather, it has been interpreted to expand it.
In summary, while states retain certain powers and have attempted various means to challenge federal authority, they cannot legally pass laws that contradict federal law. Additionally, both state and federal governments are denied certain powers by the Constitution to protect citizens' rights and maintain a balance between different levels of government.