At the centre of the row before the supreme court are a 6ft red granite monument in Austin, Texas, and two framed copies of the commandments that have been hanging in two Kentucky courthouses for five years.
The issue has assumed nationwide significance since the high-profile standoff in Alabama 15 months ago when the state's supreme court justice lost his job after he refused to remove a two-tonne granite monument of the commandments from the rotunda of the state courthouse.
The Bush administration, which owes its re-election in no small part to the religious right, has filed briefs urging the supreme court to uphold the displays, calling the Ten Commandments "a uniquely potent and commonly recognised symbol of the law".
Jay Sekulow, chief counsel of the American Centre for Law and Justice, a law firm set up to support evangelicals and other religious communities in their legal battles, argues that the commandments have become so established that they are invested with secular meaning and are now "uniquely symbolic of law".
The case was brought by a homeless former lawyer, Thomas van Orden, who is based in Austin.
"I didn't sue Christianity or Judaism; I sued the government," he told the Associated Press. "It was filed to uphold the principles of the first amendment."
Mr van Orden, who had his licence suspended several times for failing to pay fines and charging for work he did not do, will not be arguing the case in the highest court in the land, and is not sure whether he will go to Washington to hear it debated. "It takes money to go to Washington," he said.
Instead, it will be argued by Erwin Chemerinsky, of Duke University law school. "There is no secular purpose in placing on government property a monument declaring 'I am the Lord thy God'," wrote Mr Chemerinsky in his brief.
Arguing the case for Texas will be the state attorney general, Greg Abbott.
"I hope and believe the United States supreme court is not going to force agnosticism upon the people of this state and this country," Mr Abbott said.
"The first amendment was never intended to remove all religious expression from the public square."
The US supreme court itself boasts a depiction of Moses, holding the tablets, on a marble frieze alongside other "great lawgivers of history".