Airbnb is taking its beef with the city of San Francisco to court.

The short-term rental company filed suit today over a new law that requires Airbnb to verify that its hosts have registered with the city before showing ads for their homes online. The suit aims to block the law from going into effect as scheduled on August 1.

San Francisco legislators passed the law earlier this month in an effort to combat the housing crisis in the city, but Airbnb and technology advocacy groups argue that the new rules violate the Communications Decency Act.

“This legislation ignores the reality that the system is not working and this new approach will harm thousands of everyday San Francisco residents who depend on Airbnb. It also violates federal law,” Airbnb said in a blog post announcing the suit. “This is an unprecedented step for Airbnb, and one we do not take lightly, but we believe it’s the best way to protect our community of hosts and guests.”

This is an unprecedented step for Airbnb, and one we do not take lightly. Airbnb

San Francisco already requires Airbnb hosts to go through a rigorous registration process that involves acquiring a business license, in-person registration, quarterly reports on when guests are sleeping in the home (as opposed to when the owners are), and a list of all the furnishings in the home that a guest might use, down to the sheets and towels.

The process is intended to help the city weed out commercial renters who are taking their properties off the housing market and listing them exclusively on Airbnb. Doing so might earn a homeowner more money, but it also takes housing stock away from a city that desperately needs all the housing it can get.

Understandably, many hosts opt not to go through the cumbersome registration process — and the new law puts Airbnb on the hook to make sure its hosts comply. The law requires Airbnb to make sure hosts register, and the company faces $1000 per day fines if it does not.

Airbnb launched a campaign asking its hometown to streamline the registration process, but the company is taking its fight to federal court, too.

In documents filed this afternoon, Airbnb argues that the new law violates Section 230 of the CDA, which protects websites from being held liable for content provided by their users. Airbnb argues that the city should hold hosts accountable for registering instead. “Instead of punishing Airbnb for publishing unlawful listings, the City could enforce its short-term rental law directly against hosts who violate it,” Airbnb’s filing suggests. “Removing these listings would cause a substantial disruption to Airbnb’s business and have a significant detrimental effect on Airbnb’s goodwill and reputation among both hosts and guests, thus threatening irreparable injury to Airbnb’s business.”

It’s the same principle for online vendors of alcohol and cigarettes. City Attorney spokesperson

Advocacy groups like the Electronic Frontier Foundation and The Center for Democracy and Technology have agreed with Airbnb’s legal analysis. The legislation “clearly goes against what Section 230 states,” CDT policy counsel Gautam Hans wrote in a blog post.

However, the San Francisco City Attorney’s office argues that Airbnb is misinterpreting the CDA. “Nothing in San Francisco’s pending ordinance punishes hosting platforms for their users’ content. In fact, it’s not regulating user content at all — it’s regulating the business activity of the hosting platform itself,” City Attorney spokesperson Matt Dorsey said. “It’s simply a duty to verify information that’s already required of a regulated business activity.”

The CDA protects YouTube from liability when users upload violent content and eBay when sellers use the platform to trade illegal goods, but the City Attorney argues that Airbnb is less of an online business and more of a physical one. “It’s the same principle for online vendors of alcohol and cigarettes. Businesses that sell those products have a legal duty to verify the age of their customers, whether it’s online or at the corner store, so they don’t sell alcohol and cigarettes to children. They, too, are required to verify information that’s already required for their regulated business activity,” Dorsey added.

In addition to the alleged CDA Section 230 violation, Airbnb also claims that San Francisco shouldn’t require the company to turn over information about its users without a subpoena. Airbnb argues that the city’s requirement to disclose users’ registration data also violates the Stored Communications Act.