Final answer:
The state action doctrine prevents states from nullifying federal laws and actions. It is supported by the supremacy clause, which places federal law above state law, and the Constitution, which restricts both federal and state actions. Supreme Court decisions have upheld these principles, striking down state challenges to federal authority.
Step-by-step explanation:
The state action doctrine relates to the limits of state powers in relation to the authority of the federal government. Under this doctrine, states cannot declare federal laws null and void; this is a principle inherent to the structure of federalism in the United States. States are prohibited from performing actions that are solely within federal jurisdiction, such as conducting foreign diplomacy or printing money. Additionally, both state and federal governments are restricted from passing bills of attainder, ex post facto laws, laws breaking contracts, or granting titles of nobility.
Through a series of historical challenges and Supreme Court rulings, it has been established that federal law supersedes state law. For instance, when states assert nullification to block federal laws they consider unconstitutional, the courts have typically rejected these claims. The Supreme Court has the authority to strike down both federal and state laws and actions if deemed unconstitutional. The principle of national supremacy, stemming from the supremacy clause of Article VI, supports the idea that legitimate national laws trump conflicting state or local laws.
Examples of limitations on state action include the Supreme Court's decision to strike down part of a federal law that compelled state and local law enforcement to conduct background checks for prospective gun purchasers and the ruling that states could not be forced to expand Medicaid under the provisions of the Affordable Care Act.