The Justice Department might not be able to reverse a blistering district court opinion refusing to block the $85.4 billion merger of AT&T Inc. and Time Warner Inc., which has closed, but a reversal isn’t the only reason the DOJ might want to risk appealing that opinion.

Judge Richard Leon of the U.S. District Court for the District of Columbia based his June 12 opinion about the AT&T-Time Warner deal largely on facts and his determination of which witnesses were more credible. That’s hard to challenge on appeal. Leon’s fact finding gets a deferential “clear error” review in the U.S. Court of Appeals for the D.C. Circuit, and his credibility determinations get special deference that make them difficult to reverse.More at Bloomberg News