Libertarian is a broad term. You have anarcho-capitalists, minarchists, libertarian socialists, etc. The least authoritarian, an-caps, do wish that everything was voluntarily. Then there those in America who I'll call practical libertarians who simply want to follow the U.S. Constitution more closely than has been done while still adhering to libertarian principles.
In this case, they believe that the federal government should be involved in defense and aiding interstate commerce (without abusing the terminology as has been done by Congress), and leave everything else, as the 10th amendment states, up to the state.
In this case, they believe that the federal government should be involved in defense and aiding interstate commerce (without abusing the terminology as has been done by Congress), and leave everything else, as the 10th amendment states, up to the state.