Protects states rights to choose laws within their states. Emphasizes that federal government is of limited and enumerated powers, so that the first question when it uses its power is not whether it violates someone's rights, but wether it exceeds the national goverments reach.
"The power not delegated to the United States by the consitution, nor prohibitied by it to the States, are reserved to the States respectivly, or to the people.".
