The letter is Zillow’s latest in the antitrust lawsuit filed by Compass in mid-June, in which the Robert Reffkin-helmed firm claims that Zillow’s listing access standards break Federal antitrust laws. Announced in early April, Zillow’s listing access standards policy bans listings from its site if they have been publicly advertised for more than one business day before being input into the MLS and made available for display on IDX and VOW websites.