In late May, Zillow put a rule into effect (announced in April) that bans listings that have appeared elsewhere for 24 hours before going on Zillow. Compass alleges that the "Zillow ban" violates federal antitrust laws. "No one company should have the power to ban agents or listings simply because they don't follow that company's business model." That's what Zillow is doing in real estate. A Zillow spokesperson told CBS Moneywatch that the company will fight the "unfounded" claims in court.