What is the proper role of the government? What are its central responsibilities? What are the limits to governmental power?

The proper role of a democratic government is to govern for the people. The government's duties include, to establish justice, to form a more perfect union, to insure domestic tranquility, to provide for the common defense, to promote the general welfare, and to secure the blessings of liberty.
The Democratic Government should be a representation of its general population as well as representing what the people want and need. The central responsibilities of our government are protecting its citizens, and contributing to sustainable economic development. This means that the government should work toward bettering the lives of its citizens.
There are limits to governmental powers. The government, just like its citizens, is restricted by law. The rights and regulations of government are detailed in the constitution.

Many people have written about the proper role of government over the past several thousand years, and they have offered up a wide range of different opinions on the topic. For example, in Mesopotamian law codes, the ruler was thought to be an intermediary between the divine and the human and was understood as a protector of his people. Some of this attitude, with its inherent paternalism, was seen in notions such as the "divine right of kings" in the Renaissance, in which the Christian monarch combined secular and religious powers.
In the Enlightenment, many philosophers began to regard government as representing the will of its citizens and being in service to them. A government's legitimacy was contingent on the consent of the governed. John Locke was particularly influential in this line of political thought, and his work influenced the Constitution of the United States.
In modern democratic societies, government functions to perform tasks which are necessary for the collective good in a way representing the will of the governed. For example, governments are involved in police work and are responsible for dealing with crime, firefighting, and utilities, such as building aqueducts or other systems to provide cities with water. Governments may also enforce property rights. Defense, whether this involves the maintenance of standing armies or the establishment of militias in times of conflict, diplomacy, and relations with other countries are also typical functions of governments.
Governments vary in their economic roles: some economies are directed or managed by the state, while others simply provide legal frameworks within which free enterprise can operate. Some governments are organized to interfere as little as possible with the liberties of their citizens so long as those liberties do not harm others, while other governments attempt to regulate many different aspects of citizens' lives.