A study of political science is an exploration of the nature and distribution of power. A federal system is a democracy and one of the many models for sharing power, within a nation.
Political science has a long history, stretching from the earliest times, when humans began to form groups and tribes, which were the precursors of modern nationalist governments. It is impossible to take politics out of the equation, when people live together in a community.
For a society to sustain itself, it has to have a clear political structure, which can make the vital decisions for the community as a whole. When we decide to live in a community, we need to agree on matters that concern it.
That is, there has to be a clear definition of what is the distribution of power within an organization, a community, a state, or a nation. There are different ways in which power could be distributed in a nation, to maintain its sovereignty and achieve welfare goals for its citizens. The federal system is one of the many systems that could be adopted by countries.
Federal system is a democratic power distribution model, that involves the division of power between a central government entity and local governments. The degree of division in power between center and states of a democratic nation may vary.
Generally, the most vital powers that relate to security and stability of the whole nation, are granted to the center, with states sharing subsidiary responsibilities. This distribution of powers, rights, and duties is decided by the constitution of a nation. The setting up of a federal system of government, is based on the establishment of a constitution, which describes the power equation between center and states.
The legislative, executive, and judicial powers are shared between the center of a federal government and its subsidiary states. The degree to which states are granted freedom, with respect to these three aspects may vary. Such a system may be symmetric, with all states granted equal amount of local power, under the aegis of a central government, or asymmetric with certain states granted more powers.
To sum it all up, a federal system is like the structure of a solar system, with a central government in place of the Sun and state governments in place of the orbiting planets. This is not an exact analogy, but I think it serves the purpose.
This system has evolved over time, with legislation correcting the anomalies through trial and errors. The exact opposite of such a system is a unitary system.
Pros and Cons
No democratic system is perfect and none of the models related to the sharing of power are any close to achieving perfect harmony among its constituents. Let us first explore the pros of this system of government.
One of the prime advantages is the certain degree of autonomy, which a state may get, in deciding its local laws, despite being a part of a whole. Local laws can be modified, according to local needs and demands. Another advantage is the simplification in governance, achieved through the distribution of power.
Local problems can be dealt at that level, without letting them gravitate to the national level. The central judiciary acts as the arbitrator, when there are disputes between states or between states and center. The nature of the judicial, executive, and legislative departments of governance is hierarchical, which simplifies the decision-making process.
Now let us see what are the cons of the system. One problem raised by anti-federalists is the phenomenon of absolute power being granted to the center, which can go to an extreme, leading to an autocratic system. It is in the very nature of power that it gravitates to the one who know how to wield it. Another con is the disconnect that it may create between the center and the states, leading to insensitivity on center's part, related to local problems.
The central axle of the government may be too far from the periphery, in effectively dealing with its problems. However, these problems can be worked upon, by creating more effective administration systems. The size and scale of a nation matter, when considering a political system that is appropriate for its governance.
A better synchronization between center and states is needed. For large nations, adopting a federal nature of government is inevitable, as a direct central control is not possible.
We have an example of a federal system, in the form of the government of United States of America. Other examples are governments of Canada, Australia, and Brazil. While it is certainly not the perfect form of government or distribution of power, it can be made to work, despite its shortcomings.