The 20-year battle over the Mount Soledad Veterans Memorial Cross went to the 9th U.S. Circuit Court of Appeals on Thursday.
The American Civil Liberties Union (ACLU) has long fought to have the cross removed, saying its display on public land is unconstitutional.
Last year, U.S. District Judge Larry Alan Burns disagreed and ruled the cross is more of a secular memorial to war veterans than a statement promoting religion.
"The court finds the memorial at Mt. Soledad, including its Latin cross, communicates the primarily non-religious messages of military service, death, and sacrifice," Burns wrote in his decision. "As such, despite its location on public land, the memorial is constitutional."
The 43-foot cross currently sits on top of San Diego's Mount Soledad. It was built more than 50 years ago as a memorial to veterans of the Korean War.
"Tearing down this veterans' memorial would be a disgrace," Kelly Shackelford, chief counsel of Liberty Legal Institute and attorney for The American Legion, told the Christian Post.
"It would not only dishonor those who have spilled their blood and given the ultimate sacrifice for their country, but it would open up veterans memorials nationwide to attack," she said.
It is unclear how or when the judges will rule.