The Bill of Rights
Congress convened for the first time in 1789. One of its first acts was to debate and propose a series of amendments to the Constitution to be known as the Bill of Rights. Why did a newly adopted Constitution need to be revised immediately? During the ratification debates, several states were concerned that the federal government would become too powerful and would have the potential to abuse individual liberties. To address these concerns, proponents of the Constitution promised that they would consider adding a citizens' bill of rights after the Constitution took effect.
Although James Madison did not share these concerns, he honored the promise by proposing a number of amendments in June, 1789. Congress passed 12 of them by the necessary 2/3 majority, 10 of which were eventually ratified by the states. Collectively, these 10 amendments are known as the Bill of Rights.
The Bill of Rights places specific limits on the power of the federal government to interfere with individual liberties. Six of the amendments protect the freedom of expression or guarantee due process of law. (Each of these freedoms is discussed more completely in the Civil Liberties chapter of your textbook.)
Most Americans are not aware of the fact that the Bill of Rights originally only applied to the federal government, and not to state governments. In other words, the Bill of Rights originally did not prevent state governments from abusing the rights of free speech, freedom of religion, etc. It took another constitutional amendment -- the Fourteenth -- and the U.S. Supreme Court to change that.