Even after the draft U.S. Constitution was finished in 1787, the arguments weren't over. The Federalists -- advocates of a strong central government -- wanted the states to ratify the Constitution, but were opposed by Anti-Federalists who were concerned that states would give up too much power and that the document didn't adequately protect certain basic rights. It took a compromise in the form of a set of amendments -- the Bill of Rights -- for them to agree to adopt the new document.
Compromise and Assurances
In order to address the concerns of Anti-Federalists, who held that the Constitution gave the national government too much power, Federalists agreed to add the amendments in the Bill of Rights to the Constitution once it had become law through ratification by at least nine states, which was done by 1788. This set of amendments addressed concerns that the original document did not guarantee rights such as freedom of expression, freedom from unreasonable search and seizure or trial by jury, for example. The compromise was successful: All states had ratified the new Constitution by 1790, and by the end of 1791, had also approved the 10 amendments that comprise the Bill of Rights.