Zillow’s listing standards policy is slated to go into effect on Monday, but not if Compass gets its way with the court.

Real estate brokerage company Compass has filed a lawsuit against Zillow, claiming the popular real estate website is refusing to accept home listings for properties that have been initially advertised for sale elsewhere.

At the heart of the rift is a disagreement over industry norms that could change how buyers shop and how sellers list homes.