The NAR created a bylaw in 2003 that allowed members to opt out of sharing their listings with online real estate brokerage firms. The DOJ wants the rule struck down because it discourages competition and hurts the consumer. The NAR had been negotiating with the DOJ and had modified the rule but not to DOJ’s satisfaction.[Valuation Review: Paid Subscription] 
DOJ states that the original rule:
prevents consumers from receiving the full benefits of competition and threatens to lock in outmoded business models and discourage discounting
and the revised rule still:
discriminated against “brokers who use the Internet to more efficiently and cost-effectively serve home sellers and buyers.”
Besides going after NAR for limiting competition, the DOJ seems to go after the broker business model, saying the rule was forcing the use of a dated business model.