According to the doctrine of preemption, which statements is true?

The doctrine of preemption is based on the supremacy clause. The doctrine essentially states that if a federal law preempts state law, then the state law is declared invalid. Therefore, a federal court may require a state to refrain from enforcing the law if the behavior conflict with federal law.

Explanation:

the results of roman expansion produced social conflict and civil war. julius caesar gained power and became a dictator but was then assassinated. the reign of augustus began a long period of imperial rule and peace in the roman empire. rome faced the problems of how to maintain peace, law, and order.

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brainliest?

answer: i looked it up

explanation: in 1955 in montgomery, alabama, a girl refused to give up her seat on a public bus. the girl was black, and the passenger looking to take her seat was white. this is a familiar tale, but it's not about rosa parks. the girl in the story is a 15-year-old high school student named claudette colvin, and this act of defiance occurred nine months before rosa parks did the same thing. colvin was arrested, and her case is what led to the u.s. supreme court's order for the desegregation of alabama's bus system. so, why don't we know colvin's name? "later i had a child born out of wedlock; i became pregnant when i was 16," colvin says. "and i didn't fit the image either, of, you know, someone they would want to show off.