Members of a presidential study commission on antitrust will decide today whether to allow American Telephone & Telegraph Co.'s top lawyer to testify before it about the company's government antitrust case.

The staff of the commission initially had turned down. AT&T's request to have Harold Levy, AT&T general attorney, appear before the commission on grounds that the case is currently in litigation and his testimony would then seem to be of a "partisan" nature.

Levy was the only person involved in a pending large case to ask to appear before the commission.

At the opening yesterday of the first of three days of hearings on problems of complex antitrust cases, John Shenefield, assistant attorney general for antitrust and the commission's chairman, asked the panel as a whole to decide whether to permit Levy to testify. His request came after Levy reacted indignantly to the staff decision to allow him not to participate as a live witness but only to submit written testimony.

The commission has retained a consultant to study pending antitrust cases, and Levy had been asked by the staff to submit his documents to him.

"We frankly find it difficult to understand how the commission could possibly refuse a request to testify from the attorney responsible for defending what is probably the most complex antitrust litigation ever undertaken by the government," Levy wrote the commission.

Shenefield reminded the panel that he was the ultimate supervisor of the AT&T case, in which the Justice Department is charging AT&T with monopoly. He said he would ask the staff on the case not to appear at the commission hearings to avoid litigation of the issues of the case at the hearings.

During a day of testimony yesterday, panels of private lawyers, government lawyers and judges seemed generally to agree that exercise of firm control of a case by judges would be a major factor in expediting complex cases.

"I think setting the trial date is the key," Fred Bartlit, a member of the private bar, told the panel. "A district judge - at the beginning - can and should set a firm inflexible trial date. It solves all problems," he suggested. It forces the lawyers to focus on primary issues and forces them to forgo what could be dilatory and harrassing tactics that would otherwise delay the trial date, he said, adding "I've never seen a case that couldn't be ready for trial in 24 months."

Steve Susman, a plaintiff's lawyer from Houston who works on a contingency fee basis, said one problem in getting antitrust cases to trial is that judges already, and mistakenly, believe they are all complex and therefore put off scheduling them on the docket.

Although government attorneys were divided on the issue, members of the private bar and judges were opposed to the setting up of a special panel of judges to try antitrust cases.

"We're against the idea of creating specialist judges," District Judge Charles Renfrew told the panel. "The techniques for expediting antitrust cases are equally applicable to all complex cases."

Most panelists also agreed that no major changes in discovery and other court rules and procedures were needed. "I don't see the need for changes in the system." Hugh Morrison, deputy assistant attorney general for antitrust, said. "It's a people problem."