The U.S. Department of Justice last week sued AT&T to block its planned acquisition of Time Warner, saying the combination could raise prices for rivals and pay-TV subscribers while hampering the development of online video. "We're prepared to make concessions," AT&T's CEO, Randall Stephenson, said at an Economic Club of New York luncheon. "What we put in the filing is a concession." AT&T and Time Warner said in a filing on Tuesday that Time Warner's Turner unit had offered its distributors licensing terms that forbid Turner from "going dark" on any distributor for seven years after the deal closes if they were to reach an impasse in negotiations. Blackouts are considered to be a negotiating tool in carriage disputes between distributors and programmers. Sources told Reuters earlier this month that the Justice Department had demanded significant asset sales in order to approve the deal and that it asked AT&T to sell either CNN-parent Turner or AT&T's DirecTV business.