A California real estate powerhouse has launched a legal war against brokerage giant Compass, accusing the company of trying to rig the housing market in its favor by keeping lucrative home listings hidden from competitors while cashing in on everyone else’s data.

California Regional Multiple Listing Service (CRMLS) filed a federal lawsuit against New York-based Compass, escalating an increasingly nasty feud over whether real estate agents can publicly advertise homes without sharing those listings with competing brokers, according to Inman.

The explosive legal showdown could reshape how homes are bought and sold across California and potentially the rest of the country.

CRMLS, one of the nation’s largest multiple listing services, filed the complaint Oct. 5 in the U.S. District Court for the Southern District of New York, just one day before a deadline Compass had set for the organization to back down.

At the heart of the bitter dispute is a controversial practice involving so-called “office-exclusive” listings — properties that brokerages keep off the MLS, the massive database agents use to share homes for sale.

Compass argues homeowners should have the freedom to publicly advertise their properties without being forced to place them on the MLS.

But CRMLS claims the brokerage wants to have its cake and eat it too.

“What the rules do not permit is having it both ways — publicly marketing a property to attract buyers while simultaneously withholding that property from the MLS cooperative,” CRMLS attorneys wrote in the complaint.

The organization argues Compass wants access to thousands of competing agents’ listings while keeping its own publicly marketed properties out of the shared database.

CRMLS CEO Art Carter blasted the brokerage’s position, accusing it of attempting to exploit a system built on cooperation.

“Compass has rejected our reasoning and is advancing legal arguments that we believe are unfair and would allow Compass to free ride on the hard work of cooperating CRMLS subscribers,” Carter said in a statement.

The showdown intensified after Compass fired off a formal demand letter Sept. 8, threatening legal action unless CRMLS agreed by Oct. 6 to stop penalizing agents who publicly advertise office-exclusive listings.

Compass CEO Robert Reffkin subsequently took the fight public, declaring on social media that the company was “preparing a federal antitrust lawsuit against CRMLS.”

He also pointed to a 2018 CRMLS seller exclusion form that he argued showed the organization previously permitted homeowners to publicly market properties without immediately entering them into the MLS.

Compass insists its position is about protecting homeowners’ choices, not gaining an unfair competitive advantage.

A Compass International Holdings spokesperson told Inman that “homeowners should be able to publicly market any listing — including office-exclusive listings — without their agent facing thousands of dollars in fines.”

The company also argued that MLS organizations serving more than 350,000 agents across 12 states already allow the practice.

But CRMLS isn’t buying it.

Under its current rules, brokers generally must submit residential listings to the MLS within one business day of publicly marketing them.

Agents can keep certain listings exclusive to their brokerage, but those properties cannot be publicly advertised while remaining outside the shared system.

CRMLS is asking a federal judge to declare those requirements lawful under federal and California antitrust laws and permanently block Compass from pursuing antitrust claims challenging the rules.

The organization is also seeking attorney’s fees and costs.

Meanwhile, CRMLS is rallying the real estate industry behind its cause, announcing plans for an MLS Cooperation Legal Defense Fund to help defend listing transparency and cooperation.

“I want to be clear: this case is about more than defending CRMLS from a lawsuit,” Carter said. “It is about protecting a marketplace that works for all real estate professionals and consumers.”

With both sides digging in, this court battle could have major consequences for homebuyers, sellers and the agents battling for their business.

And the fight over who gets to see America’s homes for sale is only heating up.