What is the purpose of the Preamble?

The purpose of the Preamble is to state the goals of the Constitution and identify the source of its authority, providing the introductory paragraph that explains why the document was written and what it is meant to accomplish. The Preamble's full text reads: We the People of the United States, in Order to form a more perfect Union, establish Justice, insure domestic Tranquility, provide for the common defence, promote the general Welfare, and secure the Blessings of Liberty to ourselves and our Posterity, do ordain and establish this Constitution for the United States of America. Gouverneur Morris of Pennsylvania drafted the wording on the Committee of Style at the Constitutional Convention in September 1787, polishing earlier drafts that had begun by listing the states individually.

The opening phrase We the People establishes the source of authority. The Constitution does not derive its power from kings, divine right, the states acting individually, or any prior government. It comes from the American people, acting collectively. This grounding makes popular sovereignty foundational to the American constitutional order.

The Preamble then lists six purposes the Constitution is meant to achieve. To form a more perfect union meant fixing the inadequate union of states under the Articles of Confederation, which had nearly collapsed by 1786. To establish justice meant creating courts and laws capable of fair and uniform administration. To insure domestic tranquility responded to events like Shays' Rebellion in 1786 by giving the federal government tools to keep public order. To provide for the common defense meant building a unified national military rather than relying on thirteen separate state militias. To promote the general welfare authorized federal action for shared prosperity. To secure the blessings of liberty for the present generation and for posterity tied the Constitution explicitly to the cause of the Revolution.

The Preamble does not grant powers itself, as the Supreme Court confirmed in Jacobson v. Massachusetts in 1905. The grants of power come in the articles that follow. But the Preamble provides interpretive guidance for those grants and articulates the goals against which government action can be measured. Schoolchildren memorize the Preamble because it captures the entire purpose of the constitutional project in a single sentence of fifty-two words.