WASHINGTON — AT&T is seeking to put the head of the Justice Department’s Antitrust Division on its witness list in a trial over the government’s decision to block the phone giant’s $85 billion merger with Time Warner, according to two people with knowledge of the pretrial activity.

The company’s request for the antitrust chief, Makan Delrahim, to testify is highly unusual. By putting Mr. Delrahim on the witness list, AT&T is effectively forcing him to defend his own decision to oppose the blockbuster merger. The trial over the Justice Department’s lawsuit to stop the deal is scheduled to begin on March 19.

“I never heard of something like that happening in my time there,” said John M. Newman, an assistant professor of antitrust law at the University of Memphis School of Law and a former trial lawyer for the Justice Department’s Antitrust Division. “It’s a big nasty move to poke a finger at the other side by calling its counsel as a witness.”

Mr. Delrahim was included in a list of witnesses submitted to the court by AT&T in recent days, according to two people with knowledge about the company’s demands, who asked to remain anonymous because the details were confidential. AT&T has also asked for internal communications between Mr. Delrahim’s office and Attorney General Jeff Sessions, they said. As part of that request, AT&T has also asked for email, phone and other communications between the White House and officials in the Justice Department, the people said.