Final answer:
Preemption is a concept linked to the supremacy clause of the Constitution, making federal law superior to conflicting state laws. The Tenth Amendment is the source of powers reserved to the states, ensuring a federalist system. The full faith and credit clause ensures states respect each other's legal proceedings, contributing to interstate relations.
Step-by-step explanation:
The doctrine of preemption is rooted in the supremacy clause of the Constitution. According to the supremacy clause, the Constitution and federal law generally take precedence over state laws and even state constitutions. When state law conflicts with federal law, federal law typically prevails, thus the federal government has the ultimate authority in certain areas.
The source of powers "reserved" to the states can be found in the Tenth Amendment. This amendment specifies that powers not delegated to the federal government by the Constitution, nor prohibited by it to the states, are reserved to the states or to the people, thus establishing the federalist system of shared power between state and federal governments.
Furthermore, the "full faith and credit" clause is relevant to interstate relations. This clause in Article IV, Section 1 of the Constitution requires states to respect the "public acts, records, and judicial proceedings" of other states. This clause helps to ensure consistency and legal continuity across state lines.