Civil libertarians and some religious groups say a bill to erect a Ten Commandments monument on the grounds of the state Capitol is a clear violation of the U.S. Constitution and are urging Gov. Brad Henry to veto the measure.

Similar displays elsewhere, including a Ten Commandments monument at the Haskell County Courthouse in Stigler, have drawn numerous legal challenges, including some that have reached the U.S. Supreme Court.

Rep. Mike Ritze, the House author of the bill, stressed the historical significance of the Ten Commandments, which he said are an important foundation of the laws and legal system of the country, and said the display is not a religious one. He said hundreds of similar displays appear in public spaces across the country, including images of Moses and the Ten Commandments at the U.S. Supreme Court building in Washington.

"The Ten Commandments were authored by the Jewish God that we as Christians accept, but that's not the reason for the display," Ritze, R-Broken Arrow, said Tuesday, one day after the state Senate overwhelmingly approved the measure. "It's strictly a historical display."

But opponents say touting the historical relevance of the Ten Commandments is simply an attempt to draw attention away from the religious nature of the commandments and protect the monument from a possible legal challenge.

"Even though in the bill it states that they are not preferring one religion over another, we argue they are," said Tamya Cox, legislative counsel for the Oklahoma chapter of the American Civil Liberties Union. "By allowing this monument to be placed, you are highlighting Christianity over any other minority faith."

Most legal challenges center on the Establishment Clause of the First Amendment, which states that "Congress shall make no law respecting an establishment of religion, or prohibiting the free exercise thereof."

Ritze points to a similar Ten Commandments monument at the Texas State Capitol that the U.S. Supreme Court ruled was constitutional, but Cox said that case was different because the Texas monument was erected 40 years ago and was placed in a park with several other historical markers.

The nation's highest court ruled in 2005 that Ten Commandments displays on government property must be evaluated on a case-by-case basis. Indeed, on the same day the court allowed the Texas display, it ruled against Ten Commandments displays inside two Kentucky courthouses.

The justices said Ten Commandment exhibits would be upheld if their main purpose was to honor the nation's legal, rather than religious, traditions, and if they didn't promote one religious sect over another.

Regardless of what lawmakers say about their intent, the question of whether the Legislature is endorsing one religion over another will be a critical component to any legal challenge, said Micheal Salem, a Norman attorney who specializes in constitutional law.

"They can say whatever they want," Salem said. "The ultimate analysis of this will depend on the facts on the ground."

Meanwhile, a number of groups are urging Henry to veto the measure, which passed overwhelmingly in both the House and Senate.

"We should be more concerned with following the Ten Commandments rather than merely posting them on government property," said K. Hollyn Hollman, general counsel for the Washington, D.C.-based Baptist Joint Committee, a religious liberty organization. "Religion flourishes best when the separation of church and state is protected."

Cox, of Oklahoma's ACLU chapter, said she's concerned about the message such a monument will send to non-Christians who visit the state Capitol.

"If people want to put these monuments on private property, we'll defend that right every day," she said. "But we have a lot of people of minority faiths and people of no faith who go to the Capitol daily, and this is an unwelcome mat for those Oklahomans as well."