They cannot
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The Tenth Amendment of the Constitution of the United States explains that those powers not explicitly detailed in the Constitution are reserved to the states (and the people). Therefore, if the law is not in voilation of precedence or the US Constitution, the federal government cannot prohibit the law. However, the implied powers, or those referenced in the "necessary and proper" clause in Article I, Section 8 of the Constitution, permit Congress to impose laws to effectively execute current laws and those principles in the Constitution. Thus, the federal government can deem a law "unconstitutional" or improper and therefore prevent the law from being passed. Additionally, if that state takes action in accordance with or against foreign nations or attempts to establish individual correspondence, relationships, or treaties with other nations - actions lacking federal approval or undermining the principles for which the nation stands - that law can be REVOKED.
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A state law is created by the state and only pertains to that single state. A federal law is created by the national government and is enforced throughout the whole nation. Federal law overrides state law.
Federal. The dual government is set up in such a way that if federal and state are in conflict, federal trumps. The order is as follows: Federal constitution Federal statute Federal case law Federal regulations and administrative law State constitution State statute State case law State regulations and administrative law
Only when a state tries to use a power specifically defined for the federal government under the constitution
The federal government uses tax laws and funding to force the states to act in certain ways (drinking), if each state could ignore what the federal government says they would be eliminating its power.
The federal law overrides the state law. The federal government is the "supreme law of the land," meaning that whatever it says goes. For example, a state can pass a law stating that everything has to wear blue jeans on Tuesday. However if the federal government passes a law that everyone has to wear red pants on Tuesday, then everyone in that state and the rest of the country has to wear red pants on Tuesday.
Reserved
a national economy and a strong federal government
yes
Read the US Constitution . . Powers not specifically granted to the Federal Government are reserved to the States. (paraphrased)
supremacy clause- federal law ranks supreme over state laws
Nullification
a national economy and a strong federal government