Until very recently, it seemed that telecommunications giant AT&T’s billion deal to purchase Time Warner  would be completed by the end of December. But last week, the U.S. Department of Justice informed AT&T that it would block the deal unless it agrees to sell off one of Time Warner’s main assets — Turner Broadcasting, which includes cable news channel CNN. AT&T says it won’t sell CNN or other key assets as it attempts to acquire Time Warner, and a court battle seems likely. Wharton legal studies and business ethics professor Herbert Hovenkamp and Hemant Bhargava, a professor of technology management at the University of California-Davis, joined Knowledge at Wharton’s SiriusXM show to discuss what’s behind this sudden roadblock in a deal that could create a new media giant. Additional coverage: AT&T’s Time Warner Deal: Big Risk or Big Reward? Pay TV Consolidation: Who Are the Potential Winners and Losers?…