D.C. Attorney General Karl Racine filed a lawsuit on Tuesday against Marriott International, Inc. for charging hidden fees and “hiding the true price of hotel rooms,” his office announced in a press release.

Racine alleges that the company’s pricing practices are against the District’s consumer protection laws. The lawsuit asks for monetary relief for the tens of thousands of District residents he says have been mislead in the price of their Marriott hotel rooms.

According to the lawsuit, Marriott’s deceptive pricing has brought the company millions of dollars in profit over the last decade. The suit is the first development in a multi-state attorneys general investigation into such practices across the hotel industry.

Marriott declined to comment on the suit, but told DCist via email that “we look forward to continuing our discussions with other state AGs.”

According to Racine, Marriott, along with others in the hotel industry, advertises room rates on price comparison sites like Expedia.com and Priceline.com that are lower than what the final cost of the room will be. Once a consumer begins the booking process, the hotel will slap on mandatory fees reflecting the true, full cost of the room.

These fees can be anywhere from $9 to $95 per room per day, and according to the lawsuit, at least 189 Marriott properties worldwide charge them. None of the at least 29 Marriott properties in D.C. appear to charge hidden fees, says a spokesperson for the attorney general’s office—but tens of thousands of D.C. residents have been subject to these extra fees, according to the lawsuit.

Sometimes the hidden fees are listed under a heading labeled “taxes and fees,” leading consumers to believe that the fees are being imposed by the government and not Marriott, the complaint states. Other times, the company doesn’t give clear explanations about what the fees actually pay for.

Racine says that consumers are increasingly turning to these sorts of price comparison sites when booking a hotel room, making it critical that Marriott and other hotels advertise room rates that are honest and accurate. “We want there to be one room price,” he says.

These mandatory fees are given a variety of labels, like resort fees, amenity fees, or destination fees, and the practice of charging them, known as drip pricing, allows companies like Marriott to bring in the same amount of profit without raising advertised room prices and potentially deterring some consumers. Drip pricing began to take off in the mid 2000’s, says Jimmy Rock, the assistant deputy attorney general for the Public Advocacy Division in Racine’s office, and since then, he says the number of properties charging these sorts of fees has increased rapidly over the last decade.

In addition to seeking monetary relief for affected District residents, the lawsuit is demanding that Marriott be “fully transparent about their prices so consumers can make informed decisions when booking hotel rooms,” according to a press release announcing the lawsuit. Racine is also seeking that the company pay civil penalties for breaking the law.

But Racine says that this lawsuit isn’t necessarily against the practice of charging resort fees—it’s about making sure that those fees are “fully and fairly disclosed to consumers in a transparent way.”

This story has been updated to reflect that Marriott declined to comment.