Pleasant Grove could be forced to remove the monuments from its parks or accept all donated monuments depending on the outcome of a Utah free-speech case heard Wednesday by the U.S. Supreme Court.

Justices wrestled with several First Amendment issues in the lawsuit over Pleasant Grove's decision to reject a monument from a little-known religious group called Summum, even though the city had previously accepted a monument inscribed with the Ten Commandments.

"That's a violation of the core free-speech principle that the government may not favor one message over another in a public forum," Summum's attorney Pamela Harris said.

The lawyer said Pleasant Grove opened the park to all monuments by accepting the Ten Commandments monument from the Fraternal Order of Eagles in 1971. It was an argument some justices seemed to have trouble swallowing.

"How far do you push that?" Chief Justice John Roberts asked. "I mean, you have a Statue of Liberty; do we have to have a statue of despotism? Or do we have to put any president who wants to be on Mount Rushmore?"

Attorneys for Pleasant Grove and the United States said governments are allowed to pick and choose which monuments to display because those monuments are "government speech."

"It chooses to display it, and then it can do whatever it wants with it," said Daryl Joseffer, an attorney representing the United States. "It can move it, modify it, destroy it, drop it at the bottom of the ocean, sell it on eBay."

While city parks have been recognized as a public forum for gatherings such as parades and protests, the same free-speech rights do not apply to permanent monuments, which take up a limited amount of space, attorneys argued.

In 2003, Summum leaders asked the city to erect a monument to the group's Seven Aphorisms, which members believe to be lesser-known instructions given to Moses by God. Jay Sekulow, a Washington, D.C., attorney representing the city, said Pleasant Grove denied Summum's request because the city only allows monuments that represent the city's pioneer heritage to be placed in the park.

"I think, when it comes to the issue of selecting monuments for its park, it's very similar to a museum curator," Sekulow said, adding that government-run museums are not required to display all paintings.

Whether the Ten Commandments monument is government speech is the issue at hand for the justices. If it is the private speech of its donors, the city would be forced to accept Summum's monument.

Harris argued the monument is the private speech of its donors because the Eagles displayed their name and logo on the monument and provided the maintenance. Justice David Souter seemed to disagree.