The National Rifle Association (NRA) has filed a lawsuit against the city of San Francisco less than a week after the city’s lawmakers unanimously passed a resolution declaring it a domestic terrorist organization.

In a lawsuit filed Monday, the NRA alleges San Francisco violated the organization’s First Amendment rights. “The resolution’s ‘terrorist’ designation is a frivolous insult — but San Francisco’s actions pose a non-frivolous constitutional threat,” the lawsuit reads. “The NRA cannot stand by and allow that to happen.”

Lawmakers in San Francisco passed the resolution on Sept. 3 in the wake of mass shootings in Gilroy, Calif., El Paso, Texas, Dayton, Ohio, and Odessa, Texas, that left a combined 41 people dead. It was originally introduced on July 30 by Supervisor Catherine Stefani, who spoke after the resolution was passed unanimously.

“The NRA has done more to perpetuate and create the sick gun violence epidemic terrorizing our country,” she said during the supervisor’s meeting to vote on the resolution. “They buy off politicians, prevent common sense gun violence legislation, prevent gun violence research and tell us and everybody that it’s video games, movies or mental illness. Every country on this earth is exposed to these issues and influences in equal measure, and yet only the United States faces this kind of mass gun violence.”

The NRA responded with a video released on Sept. 4 featuring a speech by NRA CEO Wayne LaPierre, and on Monday released a statement on Twitter saying “This lawsuit comes with a message to those who attack the NRA: We will never stop fighting for our law-abiding members and their constitutional freedoms… We will always confront illegal and discriminatory practices against our organization and the millions of members we serve.”

The resolution was passed the same day as Walmart announced it would reduce gun and ammunition sales at its stores nation-wide and requested that people refrain from open carrying inside the stores.

Write to Jasmine Aguilera at jasmine.aguilera@time.com.