The provided sources discuss the legal doctrine of preemption, particularly focusing on federal preemption of state laws in the United States. They explain that the Supremacy Clause of the Constitution establishes federal law as paramount when conflicts arise. The texts outline two main types of preemption: express preemption, where federal law explicitly states its intent to supersede state law, and implied preemption, which occurs when federal intent to preempt is not explicit. Implied preemption is further divided into field preemption, where federal regulation is so pervasive it leaves no room for state law, and conflict preemption, where state law either makes compliance with federal law impossible or obstructs federal objectives. The sources also highlight the ongoing debate between state and federal powers, with different stakeholders advocating for broader or narrower applications of preemption depending on their interests.

The primary function of the Supremacy Clause, found in Article VI, Clause 2, is to establish federal law as the "supreme Law of the Land." It ensures that validly enacted federal laws override conflicting state laws and constitutions, providing legal hierarchy and national uniformity.

Federal preemption is the doctrine that invalidates conflicting state laws when Congress exercises its legislative power to displace or override state authority. Its core constitutional basis is the Supremacy Clause, which mandates that federal law prevails over inconsistent state enactments.

Express preemption occurs when a federal statute explicitly states its intent to override state law, often through a specific clause. Implied preemption, in contrast, arises when courts infer Congress's intent to preempt state law from the federal law's structure, purpose, or comprehensiveness, even without explicit language.

Field preemption occurs when federal regulation is so comprehensive or the federal interest is so dominant that courts conclude Congress intended to occupy an entire regulatory field. A common characteristic courts look for is a "pervasive scheme of federal regulation" that leaves no room for state supplementation, as seen in areas like alien registration.

Conflict preemption applies in two main situations: first, when compliance with both federal and state law is physically impossible (impossibility preemption); and second, when state law "stands as an obstacle" to the accomplishment of federal objectives (obstacle preemption).

The "presumption against preemption" instructs that federal law should not be interpreted as superseding states' historic police powers (e.g., public health, safety) unless Congress's intent to preempt is "clear and manifest." It reflects the constitutional principle of federalism, preserving a meaningful role for state autonomy.

State common law, particularly tort law, can be affected by obstacle preemption. For instance, in Geier v. American Honda Motor Co., a state tort law requiring airbags was preempted because it stood as an obstacle to a federal regulation that gave manufacturers a range of options, including not installing airbags, reflecting a federal objective of flexibility.

The Supremacy Clause directly binds state courts by requiring judges in every state to apply federal law, even if it contradicts state law or state precedent. This means state judges cannot refuse to hear federal claims or decline to enforce federal statutes due to local disagreement.

Yes, federal agency regulations issued under valid statutory authority have the same preemptive force as federal statutes if properly promulgated. Similarly, executive agreements, when entered into pursuant to constitutional authority (especially regarding foreign affairs), can also preempt conflicting state laws.

A "savings clause" in a federal statute is a provision that explicitly limits its preemptive effect, stating that certain categories of state law are not preempted. Its general purpose is to preserve state author