Federalism gives both state and national governments the power to
issue currency.
regulate trade.
raise an army.
pass legislation.

Explanation:

Federalism is system of government in which control is separated between a national government and different state governments. In the United States, the U.S. Constitution gives certain forces to the government, different forces to the state governments, but then different forces to both.  

States have their own administrative branch, official branch, and legal branch. The states are enabled to pass, implement, and interprete laws, as long as they don't violate the Constitution.

the answer to your question is a because laws act as guidelines as to what is accepted in society. without it there would be conflicts between social groups and communities. it serves as a norm of conduct for citizens.

a)the court decides which cases it will hear