The Bill of Rights was largely adopted as a compromise measure to secure agreement to the Constitution. Many of the delegates at the Philadelphia Convention were concerned that the new proposals gave too much power to the federal government, representing an attack on the cherished traditions of republican liberty and radically devolved government.
In particular, a number of delegates were worried about the possible implications of the Constitution for states' rights. Under the Articles of Confederation, ultimate political sovereignty in America had resided with the states. And critics of the new Constitution wanted to retain this principle as far as possible. The Bill of Rights was a way of assuaging their concerns by explicitly protecting the liberties of individuals and states from encroachment by the federal government.
Though the power of the federal government has grown exponentially since 1787, the Bill of Rights still retains its relevance today. It acts as an expression of principle against which the actions of authorities—both state and federal alike—can be measured. Americans greatly cherish their constitutional rights, seeing their protection as almost sacrosanct. But the Bill of Rights's precise interpretation remains a matter of considerable disagreement, as can be seen from the often bitter debates over the Second Amendment, the right to bear arms.