The Bill of Rights is a legal declaration which is formal in nature that declares the rights of an individual that is a citizen of a country. The first Ten Amendments to the US Constitution are also referred to as the Bill of Rights due to the fact that they set out the freedom of the citizens of the US and limits government through the individual rights.
The Bill of Rights is considered a formal summation of the inalienable rights granted to citizens of a country and forms the basis of all laws that a national government can allow. If any law goes against the Bill of Rights it will be deemed to be illegal and would not be ratified by Congress.