Early next month, the full U.S. Court of Appeals for the District of Columbia will assemble to hear a case involving U.S. Food and Drug Administration log books.

The case is considered an important legal one. But it is attracting widespread attention for an unusual reason: It may provide insights into life on the only court in the United States whose members include two failed Supreme Court nominees, Judges Robert H. Bork and Douglas H. Ginsburg.

The FDA lawsuit, along with a criminal case involving computation of parole dates, will be the first heard by the full court since Bork and Ginsburg returned to the fold after being thwarted in bids to succeed Justice Lewis F. Powell Jr., who retired in June.

Bork, an outspoken conservative, was rejected by the Senate last month by a vote of 58 to 42, the largest margin of defeat for any Supreme Court nominee in history. Ginsburg, also a conservative, asked President Reagan to withdraw his nomination this month after disclosures that he had smoked marijuana as recently as 1979 while a professor at Harvard Law School.

Lawyers who often practice before the appeals court, considered the second most important in the country because it rules on key federal issues, say the upcoming arguments should give some clues to whether Bork will retain his role as undisputed leader of the court's conservative faction.

"There are many questions about what kind of role Judge Bork will play on the reconstituted appeals court," one lawyer said last week. "Will such a national rejection of his philosophy cause him to sulk and play a less active role on the court? Or will he try to regain his power base?"

Some of Bork's colleagues said the main question is whether he plans to remain on the appeals body. "There were rumors about Judge Bork leaving the court before he was nominated for the Supreme Court, and I don't see how events could have made him more inclined to stay," one judge said.

Speculation previously had centered on Bork's failure to hire law clerks for the 1988-89 court term even though those decisions are usually made two years in advance. "As far as I know, he still hasn't hired clerks," the judge said.

One judge quoted Bork as describing work on the appeals court as a "lifetime sentence to law review."

Court observers say Ginsburg's future role on the court is more difficult to assess, in part because he has been an appellate judge for only one year, not long enough to establish a substantial reputation.

One of his fellow judges predicted that Ginsburg could become the court's regulatory specialist, filling a role previously performed by Antonin Scalia, who was appointed to the Supreme Court last year. Ginsburg could make a "real contribution," the judge said.

At the same time, lawyers and others question whether his admissions of marijuana use may have a lasting impact.

"If it had been long past, it would be one thing," said a lawyer who practices before the court. "But one is in a responsible position as a law professor." The appeals court sometimes rules on cases involving small amounts of marijuana, the lawyer added.

Some observers noted, moreover, that the Justice Department has begun investigating whether an independent counsel should be appointed to pursue allegations of conflict of interest by Ginsburg in cable television matters while he was an assistant attorney general in charge of the Justice Department's Antitrust Division.

Still, several judges on the appeals court who agreed to talk last week about Bork and Ginsburg's return do not see any dramatic changes in the offing.

"I consider it a nonevent in terms of the court," said one judge. "We've missed their warm bodies," said another. A third judge added, "We'll be able to get some work done." Bork's absence during the 3 1/2-month battle over his nomination and Ginsburg's briefer departure led to disruptions in long-scheduled court proceedings, some judges said.

The judges and other observers who were interviewed asked not to be identified, and Bork and Ginsburg declined to comment.

The judges' chambers are down locked hallways, and they seldom see one another except at monthly administrative meetings. One judge said he had not seen Bork since he was nominated. Last week, Ginsburg made a rare appearance in the public halls, arriving during a Veterans Day snowstorm and sporting a yellow-banded Panama hat and matching scarf.

The FDA case will mark the first time that the 12-judge court has convened in public since a long-simmering feud among court members erupted into a open squabble in July. The conflict centered on which cases the court should consider en banc -- as a full court rather than in three-judge panels.

"The interaction of the judges on the en banc cases will be one of the keys" to determining the impact of Bork and Ginsburg's return, said one lawyer.

July's quarrel raised the issue of whether conservative judges, who for the first time in decades control the appeals court here, would seek en banc reviews of every important case decided by a three-judge panel containing a liberal majority.

Bork has championed en banc reviews. But Judge Laurence H. Silberman broke rank with fellow conservatives at the time, and four cases that the full court had agreed to hear were abruptly withdrawn from en banc consideration.

It appeared that Bork's influence had been weakened. But with Bork's nomination to the Supreme Court, the outcome remained unclear.

Bork now faces a slightly altered equation. Because of a previous vacancy on the appeals court, Silberman had become the swing vote. But next month's en banc hearings will be the first in which Judge David Sentelle participates. Conservatives will have a 7-to-5 majority.