MLS and Seattle Sounders said the flag is a political symbol, prohibited by the league's code of conduct for fans. Seattle Sounders fan group The Emerald City Supporters said in a statement on their website that the images are a symbol of the struggle against fascism, oppression and persecution.
The images, three arrows pointing left and down, were actually used by a pro-democracy, anti-fascist German paramilitary organization, the Iron Front. They actively fought the Nazis during their rise to power before World War II.
Earlier this year, MLS banned the symbol under its fan code of conduct that prohibits politics in its stadiums.
MLS is lifting this ban after two meetings with Seattle and Portland, Oregon, football fan groups and the Independent Supporters Council. The board promotes the culture of football fans and fair treatment of fans at home and away from home.
The reversal came after widespread protests across the league by soccer fans.
"We look forward to continuing the dialogue, moving away from direct action in the stands on this subject and instead focusing our energy on progressing around the table," supporters' group leaders said in an MLS statement.
League president and deputy commissioner Mark Abbott told CNN in a statement that the league will update the code of conduct for 2020 with a working group to "ensure clarity and consistency."
"This working group will include representatives from the league office and clubs and will work in collaboration with club supporter group leaders and a cross-section of diversity and inclusion specialists," continued Abbot.
An MLS statement also reaffirmed: "Their longstanding commitment to the values of inclusion and diversity, including opposition to racism, fascism and homophobia, and to the assurance that there is no room for disgusting hate speech at MLS stadiums."
How the ban started
Emerald City Supporters used an Iron Front emblem flag in a Seattle Sounders game on July 21.
"The three arrows represent our commitment to equality and inclusion," the group wrote on its website. "The three arrows have been a symbol of the struggle against fascism, oppression and persecution and to this day continue to represent these important values around the world."
After the match, the fan group received a formal warning from Seattle Sounders saying the badge violated the MLS Fan code of conduct: political signage representing an association with a political group is not allowed.
"The rights we defend are not political, they are human rights," the group responded.
Fan protests become a movement
The decision to ban the emblem of all MLS games drew instant criticism and outrage from fans across the league.
The hashtag #AUnitedFront has become a rallying cry on social media and signs throughout the league. Some fans secretly placed the Iron Front arrows on signs, others wore shirts and arm bands.
One of the most dramatic protests took place on August 23. In a major rivalry game between the Portland Timbers and Seattle Sounders, fans on both sides came together and were silent for the first 33 minutes of the game.
A joint statement by the two rival fan groups says this is a protest against MLS 'ban on images "to commemorate 1933, the year the Iron Front was dissolved in Nazi Germany."
Portland Timbers fan group Timbers Army made their message clear in a Twitter post.
"What scares you the most, MLS?" "Three anti-fascist arrows down and to the left? Or the sound of silence?"