The ACLU mission statement: The ACLU is our nation's guardian of liberty. We work daily in courts, legislatures and communities to defend and preserve the individual rights and liberties guaranteed to every person in this country by the Constitution and laws of the United States. Our job is to conserve America's original civic values - the Constitution and the Bill of Rights.
I know that the ACLU is very busy defending terrorists, child molesters, and drug dealers but if they would just take a quick break from defending these "average Americans" and read my 30 second crash course on the Constitution and Bill of Rights.
Let's start with the Declaration of Independence: We hold these truths to be self-evident, that all men are created equal, that they are endowed by their Creator with certain unalienable Rights, that among these are Life, Liberty and the pursuit of Happiness. --That to secure these rights, Governments are instituted among Men...
Our rights are endowed and guaranteed by our creator not by the constitution or laws of the United States. They are secured by our laws.
The wording of the amendments is very telling. None of them says that "government grants this right" or "these rights on guaranteed by this document." They say that "X will not be infringed" or "X shall not be violated." Examples: The right of the people to be secure in their persons, houses, papers, and effects, against unreasonable searches and seizures, shall not be violated...
...The right of the people to keep and bear arms, shall not be infringed.
The funny thing about the ACLU is that they want government, notably judges, to confer new rights on people rather than have government stay out of the way as our framers intended. Their website makes no mention of defending our clearly expressed right to bear arms but they are very concerned about invented rights such as a woman's ability to kill her baby and gay marriage.