The U.S. Dept. of Justice this week asked a D.C. court to postpone until after President-elect Clinton takes office oral arguments on the cable TV industry’s challenge to the new cable reregulation law.Turner Broadcasting and other cable programmers and multisystem operators are challenging the constitutionality of the must-carry/retransmission consent provisions of the new cable law. Oral arguments were originally set for Dec. 7 in the U.S. District Court here , but the Justice Dept. has asked that the new date be set for March 8. Justice last week announced that it would not defend the must-carry portion of the new cable law, a provision that bars cable operators from removing a broadcast station from the cable system. Justice’s decision to seek a delay in the case, however, seems to leave open the possibility that the agency might reverse course and defend must-carry under a Clinton administration. Otherwise, it’s expected that Congress would appoint an attorney to defend the cable law. In seeking the delay, Justice cited the complexity of the case, and noted that Congress does not yet have a lawyer in place to defend the legislation. The National Assn. of Broadcasters is supporting the Justice Dept.’s request for a delay, while the cable industry has voiced its opposition. A decision on whether the delay will be granted is expected within a week.