A lawsuit has been formally filed against FIFA over the governing body’s ban on supporters bringing the pre-revolutionary Iranian flag into stadiums at this summer’s World Cup.

The Institute for Voices of Liberty, a Californian non-profit which describes itself as “dedicated to advancing freedom of expression” for Iranians, had previously threatened action last month, stating they were “preparing to commence appropriate legal proceedings in case of attempts by FIFA to exclude the Lion and Sun flag.”

The group followed through on its warning on Thursday afternoon by submitting a lawsuit to the Los Angeles County Superior Court, which claimed that those who wished to fly the flag possess “protected symbolic and political speech” which requires “immediate judicial intervention.”

It is calling for a declaration that a ban is unlawful in California, that supporters are allowed to carry the old flag into stadiums, and for FIFA to pay compensatory damages for any individual banned for possession of the flag. FIFA will have the opportunity to respond.

The pre-revolutionary Iran flag, similar to the country’s official flag but featuring a lion and sun motif in the standard’s centre, is historically associated with the country’s previous Shah-led regime, which was deposed from power in 1979.

Sam Kermanian, director for the Institute for Voices of Liberty, stated his intention in the lawsuit to bring the pre-revolutionary flag to matches at Los Angeles’ SoFi Stadium and Santa Clara’s Levi’s Stadium, arguing that “California constitutional free-speech protections apply because FIFA World Cup venues function as large public gathering places open to the general public.”

When asked by The Athletic last month whether the old flag would be permitted, FIFA responded by sending a long list of prohibited items.

These included: “any materials, including but not limited to banners, flags, fliers, apparel and other paraphernalia, that are of a political, offensive and/or discriminatory nature, containing wording, symbols or any other attributes aimed at discrimination of any kind against a country, private person or group on account of race, skin colour, ethnicity, national or social origin, gender identity and expression, disability, language, religion, political opinion or any other opinion, birth, wealth or any other status, sexual orientation or on any other grounds.”

The presumption is that the pre-revolutionary flag has been deemed “political” in nature, and a source inside FIFA with direct knowledge of its position told The Athletic that this is the case. FIFA did not confirm exactly which regulation it breached and it remains to be seen how, or if, the policy is applied in practice by security officials at venues.

Some fans at the 2022 World Cup in Qatar were forced to surrender the pre-revolutionary flag when searched at stadiums, but others were allowed to take it in.

The Iranian Football Federation previously issued FIFA with a list of demands in order to ensure its attendance at the World Cup, which included “respect for the Iranian flag”, as well as enhanced security across the locations the team will visit. The United States-Israel war with Iran began in February.

FIFA was further embroiled in a similar row earlier this week, when the governing body ordered Haiti to amend a kit which portrayed rebels lifting the Haitian flag at the Battle of Vertières, deeming it to be “political” in nature. The Haitian Revolution, which took place more than 200 years ago, has been recognised as the only successful slave revolution in recorded history to have resulted in a nation governed by its former captives.

FIFA has been contacted for comment.