Final answer:
When a federal government makes a law that is contrary to a state's law, the federal law is always valid and takes precedence over the state law.
Step-by-step explanation:
If a federal government makes a law that is contrary to a state's law, the federal law is valid. According to the Supremacy Clause in the United States Constitution, federal law trumps state law in cases of conflict. This means that in the event of a clash between federal and state laws, the federal law takes precedence and must be followed by all states. For example, if a state has a law banning the use of a certain drug, but the federal government passes a law legalizing the drug, the federal law will override the state law and the drug would be considered legal.
Learn more about Supremacy Clause