The U.S. Supreme Court ruled unanimously Monday the City of Boston violated the constitution by refusing to fly a Christian group’s flag at city hall while permitting other organizations to raise their flags.

A lower court previously ruled against the group, Camp Constitution, and its director, Harold Shurtleff, finding that Boston did not err when rejecting the request to fly a so-called Christian flag as part of a nearly 20-year-old city program that allows private organizations to hoist flags of their choosing for ceremonies and events at City Hall Plaza.

Justice Stephen Breyer authored the 9-0 decision which now overturns the lower court’s ruling.

“The city did not deny a single request to raise a flag until, in 2017 Harold Shurtleff … asked to fly a Christian flag. Boston refused,” he wrote, noting that Boston approved about 50 unique flags raised at 284 ceremonies between 2005 and 2017.

Breyer also noted the city’s stated concern that flying such a flag might amount to a separate First Amendment violation: government endorsement of a certain religion.

“We conclude that, on balance, Boston did not make the raising and flying of private groups’ flags a form of government speech. That means, in turn, Boston’s refusal to let Shurtleff and Camp Constitution raise their flag based on its religious viewpoint 'abridge[ed]' their 'Freedom of speech,'" wrote Breyer.

A city spokesperson said the Wu administration is “carefully reviewing” the Supreme Court's decision “and its recognition of city governments' authority to operate similar programs.”

“As we consider next steps, we will ensure that future City of Boston programs are aligned with this decision," the spokesperson’s statement said.

Reached by phone at his home in Alton, New Hampshire, Shurtleff said he and the group are excited about the decision.

“It was never our intention ever to have a lawsuit,” he told GBH News. “We just wanted to have our ceremony to honor the Constitution and Boston’s Christian history and that was it.”

Shurtleff added if the City of Boston renews its flag raising ceremonies, Camp Constitution will submit a new application.

“I think that they will probably no longer allow any group to fly any flag,” he speculated. “And that’s fine, too. That means the Chinese Communists can’t raise their flag and that means we don’t raise our flag and that’s fine.”

This is a developing story.