Earlier this month, the sheriff of Cook County, IL, persuaded both Visa and MasterCard to end their relationships with online classifieds site Backpage.com, alleging the site is known to “promote prostitution and facilitate online sex trafficking.” Today, the website fired back with a lawsuit against the sheriff.

Backpage has continued to offer adult-oriented classified ads for escorts and massages, even as competitors like Craigslist no longer include dedicated sections for these types of services. The site has been repeatedly accused of abetting sex trafficking, but has survived legal efforts to censor the user-generated ads.

However, the Wall Street Journal reports that Backpage believes Sheriff Thomas Dart’s efforts to eliminate Visa and MasterCard as payment options for advertisers on the site are tantamount to government censorship of protected free speech.

“Sheriff Dart’s actions to cripple Backpage.com and all speech through the site are an especially pernicious form of prior restraint,” reads the complaint, filed in a federal court in Chicago. “He has achieved his purpose through false accusations, innuendo, and coercion.”

Backpage seeks damages to make up for the revenue it’s losing by not being able to accept these cards.

“Our goal is to ensure that one elected official, particularly a county sheriff, cannot dictate what speech is or is not appropriate,” the site’s general counsel tells the Journal.

American Express, which has long avoided associations with adults-only merchants like strip clubs, had already ended its relationship with Backpage for advertising in the adult section of the site.

The sheriff’s office unsuccessfully sued Craigslist in 2009, claiming its adults-only ads were a public nuisance. This time, Dart says he isn’t trying to censor anyone; he just doesn’t want credit card companies to facilitate potentially illegal transactions.

“It is regrettable that Backpage has dedicated so many resources to lawyers and lobbyists when they could be partnering with law-enforcement to seek justice for sex trafficking victims,” a statement from the sheriff’s office to the Journal read.

While Backpage has received support from some in the media for its previous First Amendment fights, others are applauding the recent decisions by Visa and MasterCard.

“Other businesses should act just as boldly to stop their brands from being associated with a website that reportedly generates millions of dollars every month through online ads for adult entertainment,” reads a recent opinion piece from the Seattle Times editorial board. “[S]exual exploitation of anyone, especially children, should not be as easy to purchase as a book on Amazon.com or takeout from Jimmy John’s.”

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