Federalism is there to limit the government and it does that by creating two separate sovereign powers. Those powers are the national government which is the whole U.S.A. and state governments which are states by themselves. This restrains the influence of both of them.
Separation of powers imposes limits by dividing the government and giving separate branches separate functions so that they can and must share power.
Almost all men age 18-25 who are U.S. citizens or are immigrants living in the U.S. are required to be registered with Selective Service. U.S. law calls for citizens to register within 30 days of turning 18 and immigrants to register within 30 days of arriving in the U.S.
