> As for conscription, it's a similar situation. The constitution allows the government to "raise and support Armies" under article I section 8. This has been interpreted to mean the usage of the resources of the nation to build an army as approved by Congress. It can be money (taxes), land (eminent domain), or people (conscription).

Conscription stems from the understanding of the militia as being universal and the express power of Congress to "To provide for calling forth the militia to execute the laws of the union, suppress insurrections and repel invasions", not from the power of Congress to "raise and support Armies".