The memorial cross at the center of a 22-year legal battle was ruled unconstitutional on Tuesday by the 9th Circuit Court of Appeals.
The Mount Soledad memorial cross, located in the desert near La Jolla, Calif., was built in 1952 to honor American veterans of the Korean War.
In its ruling the court said the 43-foot cross conveys a message of government endorsement of religion that violates the Constitution.
The American Civil Liberties Union has fought to have the cross removed. They have argued it should not be on public land.
In 2008, U.S. District Judge Larry Burns disagreed and ruled the cross is more of a secular memorial to war veterans than a statement promoting religion.
"You know I'm disappointed but I'm not surprised," said attorney Charles Limandri, who represents a group of cross supporters called San Diegans for the Mount Soledad National War Memorial.
Attorney James McElroy has fought against the cross 15 years.
"It's a great day for the Constitution," McElroy said. "It's a great day for religious tolerance."
The court said modifications can be made to the memorial make it constitutional, but didn't specify what the changes might be. A cross could still be a part of the veterans memorial.
"The court was saying it's not up to us at this point to say, 'Take the cross down tomorrow,'" McElroy said.
Supporters of the cross were outraged at the court's decision.
"Well, that's a terrible shame," said Pacific Beach resident Dennis McCarthy said of Tuesday's ruling. "This is a great tribute to our veterans."
"It's been here for how many years and its part of the community," said San Diegan Annette Kunkel. "It should stay."
"I read it as being very political and agenda driven," Limandri said. "As opposed to a real legal scholarly decision."
"I think that's a little demeaning to the court," McElroy said. "Judges just try very hard to follow the constitution."
The ruling will almost certainly be appealed to the U.S. Supreme Court.