The 4th US Circuit Court of Appeals ruled Wednesday that the 92-year-old structure was in violation of the First Amendment because it is on public land at a busy intersection in Prince George's County and is maintained with government funds. The court's decision does not address whether the monument should be removed or modified.
The defendants -- the Maryland-National Capital Park and Planning Commission and the American Legion -- argued that the cross had a nonreligious purpose and "does not have the primary effect of endorsing religion," according to the majority opinion written by Judges Stephanie Thacker and James Wynn.
But the appeals court in Richmond, Virginia, sided 2-1 with the American Humanist Association, an organization that advocates for secularism and represented several non-Christian residents of Prince George's County.
Thacker and Wynn wrote that the memorial "excessively entangles the government in religion" and "breaches the wall of separation between Church and State."
Chief Judge Roger Gregory wrote the dissenting opinion, arguing that the Establishment Clause of the First Amendment "does not require the government to purge from the public sphere any reference to religion."
The memorial was completed in 1925 using contributions from private donors and the American Legion. In 1961, the Maryland-National Capital Park and Planning Commission acquired the monument and the land it sits on, and has spent $117,000 to maintain and repair the cross. In 2008, an additional $100,000 was set aside for future reparations.
The American Legion, which was represented by the First Liberty Institute, a law firm that seeks to protect religious freedom, plans on appealing the case to the Supreme Court, said Kelly Shackelford, the president and CEO of First Liberty.
"If this is the precedent, all (war memorials) are in jeopardy," Shackelford told CNN. "The kind of sandblasting and bulldozing we're talking about would be breathtaking to most Americans."
Veterans of Foreign Wars spokesman Joe Davis said the organization has supported the defendants in the case since the beginning and will continue to do so in the appeal process.
"The wrong call was made," Davis told CNN. "Our nation should be building and protecting our memorial to our dead."
If the Supreme Court declines to hear the case, a district court judge would have to decide whether to order the removal of the cross, said David Niose, legal director of the American Humanist Association.
"It's hard to think of remedies other than removal," Niose told CNN, though he said there is the "possibility of modifying the structure."
In the majority opinion, Thacker and Wynn wrote that the parties are "free to explore alternative arrangements that would not offend the Constitution," such as removing the arms of the cross to create an obelisk.
Niose also suggested that the cross be moved to private property.
But Shackelford is opposed to modifying or relocating the monument.
"I think desecrating a national veteran memorial that's been around for a hundred years is a horrible idea," he said.