Earlier this year justices were splintered on the appropriateness of Ten Commandments displays in and near government buildings.
The court did not comment in rejecting an appeal over an "In God We Trust" inscription on the Davidson County Government Center in Lexington, N.C.
The inscription, in 18-inch block letters, was paid for with donations from individuals and churches in 2002. It is more prominent than the name of the building, according to opponents.
Charles F. Lambeth Jr. and Michael D. Lea, two lawyers who regularly practice in the North Carolina center, filed the lawsuit.
A panel of the 4th U.S. Circuit Court of Appeals said that "In God We Trust" appears on the nation's coins and was made the national motto by Congress.
"In this situation, the reasonable observer must be deemed aware of the patriotic uses, both historical and present, of the phrase 'In God We Trust,"' the court ruled.
George Daly, the Charlotte, N.C., attorney for opponents of the inscription, told justices in a filing that "In God We Trust' is the national motto, but it is also a religious creed, a statement of communal religious belief."
James Morgan Jr., the county's attorney, said that Ten Commandments displays are different from "In God We Trust" which has "been displayed for decades on government buildings and on the coins and paper money."
The case is Lambeth v. Board of Commissioners of Davidson County, 05-203.
In other decisions Monday, the Supreme Court: