A more thorough explanation:

The complete-preemption doctrine is a rule that states that a federal law can be so powerful that it can turn a state law complaint into a federal claim. This means that even if a complaint is filed in state court, it can be treated as a federal claim because of the federal law's preemptive force.

• If a state law conflicts with a federal law, the federal law will take precedence. For example, if a state law allows the use of a certain drug that is banned by federal law, the federal law will be enforced instead.
• If a state law complaint involves an issue that is covered by a federal law, the complaint can be treated as a federal claim. For example, if a state law complaint involves a violation of a federal employment law, the complaint can be treated as a federal claim.

These examples illustrate how the complete-preemption doctrine can apply in different situations. In both cases, the federal law takes precedence over the state law, and the complaint can be treated as a federal claim because of the federal law's preemptive force.