The U.S. Supreme Court on Tuesday will hear arguments over whether the city of Boston engaged in unlawful discrimination and censorship when it denied the request of a local civic organization to fly the Christian flag on a flagpole outside City Hall.
Designed in the late 1880s, the white banner with red Latin cross has been adopted by many American Protestant communities as a nondenominational symbol of their faith.
The city says its policies forbid promotion of religion on its flagpoles and that doing so would violate separation of church and state.
Hal Shurtleff, founder of the nonprofit group Camp Constitution, which brought the case, argues the flagpole was effectively treated by the city as a public forum open to all viewpoints for more than a decade.
"It's a public access flagpole," Shurtleff said in an interview with ABC News Live about his 2017 request to raise the flag at a planned Constitution Day event on City Hall Plaza.
"It's kind of ludicrous to think flying a flag on a flagpole for maybe an hour or two will somehow get people to think, 'Oh my goodness, look at the city of Boston now endorsing the Protestant or the Christian faith,'" he said.
City officials had approved 284 private flag-raising events over a dozen years, including flags to mark Veterans Day, Columbus Day, LGBTQ Pride Month and numerous ethnic and cultural communities across Boston.
Shurtleff's request was the first and only one denied, court records show.
"This is an 83-foot-tall flagpole in front of City Hall that's associated with the government. That's why, you know, this religious group wants to use it, because it carries with it some government imprimatur," said Patrick Elliott, senior counsel with the Freedom From Religion Foundation, which is backing Boston in the case. "So we say the city can control that."
In court documents, Boston lawyers also argue that approved private flag-raisings were almost always "in connection with publicly recognized days of remembrance" and that the city had "never flown a purely private flag on a random day."
Lower courts sided with the city, concluding that the flagpole was not public forum and that the city officials could exercise discretion in approving requests to raise flags on its flagpole.
"The city, for its own speech, does not want to get into the issue of religion," said attorney Doug Hallward-Driemeier, who is arguing the case for Boston. "It's said that it didn't want to fly a flag that was offered as 'the Christian flag,' because that wasn't the message that the city itself wanted to communicate."
Supporters of the policy say it also protects the city from unwanted association with divisive messages and, in this case, a flag that critics allege has been coopted by hate groups.
"The Christian flag is associated with Christian nationalism. This is the same flag that was used during the Jan. 6th insurrection," said Elliott, referencing publicly available images showing the flag being carried by some rioters as they stormed the U.S. Capitol last year. "So this is really akin to them trying to take over City Hall and saying, 'Hey, this is a Christian place.'"
Shurtleff dismissed the comparison and insinuation that the flag was a symbol of extremism.
"I don't know of any white nationalists carrying Christian flags. That may have happened, but I don't know. But this flag certainly represents Christianity and was designed by a couple of Sunday school teachers. Not exactly white supremacists," he said.
The Supreme Court has limited the display of religious symbols by governments on government property, but it has also said that public forums are different and that censorship of viewpoints there isn't allowed.
The ACLU is siding with Camp Constitution in this battle, saying a win for Boston would threaten free speech.
"When the government opens its public property for private speakers, it has to treat everybody equally," said David Cole, ACLU national legal director. "This case is really about private citizens' access to government property to express themselves. And that access is critical to our ability to speak to each other, to express our views and the like."
Boston insists it never intended to make the flagpole open to anyone, for any reason, telling the high court that if a majority sides with Camp Constitution, the city may end its flag-raising program altogether.
"We're optimistic that they will rule in our favor and that we will be allowed to raise the flag," said Shurtleff, "although I understand the city will most likely cancel its flag raising events. So we'll see what happens."