Justice Department Appeals Court Ruling Allowing AT&T-Time Warner Merger

Federal officials had challenged the deal on antitrust concerns

WASHINGTON—The Justice Department on Thursday appealed a trial judge’s ruling last month that allowed AT&T Inc. to acquire Time Warner Inc., setting the stage for a second round of legal proceedings in a blockbuster antitrust case.

The department initiated the appeal by filing a two-page notice in federal court.

The appeal comes a month...