From their own mouths:

“We have staked the whole future of American civilization, not upon the power of government, far from it. We’ve staked the future of all our political institutions upon our capacity…to sustain ourselves according to the Ten Commandments of God.”
James Madison, 1778 to the General Assembly of the State of Virginia
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“ The Law given from Sinai [The Ten Commandments] was a civil and municipal as well as a moral and religious code.”
John Quincy Adams. Letters to his son. p. 61
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“All the miseries and evils which men suffer from vice, crime, ambition, injustice, oppression, slavery
and war, proceed from their despising or neglecting the precepts contained in the Bible.”
Noah Webster. History. p. 339

Article:

REIDSVILLE, Ga. (AP) – Tattnall County officials say they didn’t know they were running afoul of state law when they let members of a Baptist church hang a framed copy of the Ten Commandments inside the county courthouse last week.
County Commission Chairman Frank Murphy said Monday that officials told members of Ella Grove Baptist Church it would be OK for them to display the biblical text inside the courthouse because it’s a historical document.
What they didn’t realize is a 2006 state law requires eight other documents, such as the Declaration of Independence, to be posted alongside the Ten Commandments to give them a historical context.
Murphy says county officials will comply with the law. But Debbie Seagraves of the American Civil Liberties Union said the county should remove the Commandments until then.

(Copyright 2010 by The Associated Press.  All Rights Reserved.)

http://www2.wsav.com/sav/news/local/article/aclu_asks_tattnall_co._to_take_down_ten_commandments_display/95278/