A system of government distributes power among different parts and levels of the state. Political scientists study the uses of power, including how power is distributed within a state. The amount of power held by the central government determines the system of government a state has.There are three main systems of government used today: unitary systems, federal systems, and confederate systems.System.olitical scientists study the uses of power, including how power is distributed within a state. The amount of power held by the central government determines the system of government a state has. There are three main systems of government used today: unitary systems, federal systems, and confederate systems. System.