Federalism is about how power is divided between national and local governments. Different professions see it differently: economists focus on efficiency, political scientists on describing arrangements, and lawyers on constitutional values. Justice Brennan believed in values guiding this division of power. The struggle between national and state governments is seen as a zero-sum game, with each gain for one side seen as a loss for the other. This tension is rooted in the idea of state sovereignty, which is central to the concept of federalism.