When discount and flat fee compensation arrangements started growing in popularity in the early 2000s some MLSes changed their membership rules or rule enforcement to make discount/flat fee MLS listings difficult or impossible. In response, the Federal Trade Commission investigated, found several violations of anti-trust laws, and entered into settlements with five MLSes to enable free competition for listings. One MLS, Realcomp in Michigan, refused to enter a settlement/consent agreement with the FTC, asserting it had the right to hide listings of discounters because such competition is detrimental to the revenue of its members. In 2006, the FTC filed a lawsuit against the Realcomp MLS alleging violations of federal anti-trust laws and squelching free competition. The lawsuit went to trial in 2007 and the FTC lost, but won the case in a 4–0 unanimous ruling on appeal in 2009.
