Followers of Summum, a bizarre Ancient Egyptian cum New Age religion practised inside a pyramid, are demanding the right to erect a large monument listing their guiding "Seven Aphorisms" next to an existing stone inscribed with the Ten Commandments in a public park.
When officials in Pleasant Grove City refused, the sect sued, arguing that a town that accepted one donated monument had to accept others.
A federal appeals court agreed, ordering the town to erect the Summum monument.
Pleasant Grove City appealed the decision and the Supreme Court will on Wednesday consider what experts say is the most important significant free speech debate of its term.
The case, which hinges on whether a public park open to some donations must accept others as well and whether freedom of speech is guaranteed in such places, is being followed closely across America.
Many of the country's most famous memorials were donated and veterans' groups are worried that theirs may soon be twinned with anti-war ones. The Boy Scouts and atheist groups have expressed similar fears.
Gregory Garre, the US Solicitor General, has warned that even the Statue of Liberty could theoretically end up with a similarly-sized monument offering a discordant view if the Summum claim is upheld.
The Pentagon cited the Summum case earlier this year when it delayed relocating to US soil a monument in Australia to 40 men killed in a Flying Fortress crash in 1943.
The attorneys general of 13 other states including Florida and Texas have backed the Utah town, whose court filing states that accepting a Statue of Liberty should not compel a community to accept a "Statue of Tyranny" as well.
Lawyers for Summum counter that the government cannot take sides in a "theological debate".
The Summum religion was founded in 1975 by a former Mormon, Corky Ra, who claimed he learned the aphorisms in telepathic conversations with divine beings.
The religion, which contains aspects of Christian Gnosticism, practices "modern mummification". Worshippers meet in a wood and steel pyramid whose interior is surrounded by gilded, mummified animals such as dogs and cats.
The Utah-based faith holds that Moses received two sets of tables on Mount Sinai.
The aphorisms – which concern the importance of psychokinesis, vibration and gender – were the first set.
The religion won similar cases against two other Utah towns, which chose to take down their Christian monuments rather than have to put up a Summum one. by Telegraph (UK).