The government yesterday outlined conspiracy and bribery charges against the chairman of the D.C. Alcoholic Beverage Control Board, its staff director and a local bar owner--twice making its lengthy and complex opening argument to two separate juries that have been assembled in U.S. District Court to decide the case.

The unusual dual jury procedure, which the prosecutors said they fear will result in a "nightmare" of logistical problems, has never before been used here in the federal court.

It was ordered by Judge Charles R. Richey after he ruled that certain prosecution evidence against the bar owner, Tommy Motlagh, could not be used by the government in the case against ABC board chairman Robert C. Lewis and staff director James E. Boardley. All defense lawyers in the case had also objected to the two-jury procedure.

A grand jury indictment charged that Lewis and Boardley guaranteed Motlagh would get a license for a liquor store in the new Hechinger Mall and that Motlagh offered them a secret interest in the store's profits. All three men have denied the charges.

The prosecution also contends that Boardley and Lewis offered a Hechinger official an interest in the store in exchange for his approval of a lease for the store at the mall, near the intersection of Benning and Bladensburg roads NE. Law enforcement officials learned of the alleged scheme when that Hechinger official came to them with an account of the alleged offer.

When conflicts in evidence arise among defendants, courts customarily hold separate trials; in this case that probably would have meant one for Lewis and Boardley and another for Motlagh. Richey, however, citing the expense and length of time that it would take to hold back-to-back trials (estimates are the case now will take a minimum of four weeks) decided instead to empanel two juries.

When the trial opened yesterday, two panels of 12 jurors and four alternates each sat in red leather chairs in the well of the courtroom--one to the right of Richey for Lewis and Boardley and one to the left for Motlagh. Each of the 32 jurors and alternates has a set of yellow plastic earphones that will be used to listen to the prosecution's extensive wiretap evidence against the three men.

In general, all the jurors will hear all the evidence simultaneously. When the restricted Motlagh evidence comes up, the Lewis-Boardley jurors will leave the room.

Richey has ordered that the Lewis-Boardley jury be sequestered in a local hotel, under supervision of deputy U.S. marshals, to try to protect them from any exposure--particularly through the news media--to the evidence that only the Motlagh jury will hear.

Before opening statements began yesterday, Richey had all the jurors assemble in the courtroom where he gave them preliminary instructions. He also advised them that while the bulk of the evidence in the case will be heard by both juries, there will come a time--because of some "difficulties" with the evidence--when the Lewis-Boardley jury will have to leave the courtroom.

What Richey does not want the Lewis-Boardley jury to hear is government evidence of a conversation between Tommy Motlagh and a close friend whom he ran into at an Atlantic City, N.J., casino shortly after news broke in February 1981 that Lewis and Boardley were under investigation by federal authorities.

Assistant U.S. Attorney Richard L. Beizer said in court yesterday that the friend, Nassar Zolfaghari, a College Park, Md., restaurateur, will testify that Motlagh told him: "Those two guys, my partners from the ABC board, they messed up. They put too much heat on Hechinger's over permits. Hechinger's went to the cops. I'm in trouble. Can you lend me some money?"

Beizer, who is prosecuting the case with Assistant U.S. Attorney David W. Stanley, did not include that piece of information in his opening statement to the Lewis-Boardley jury, but he did describe it to the Motlagh jury later in the afternoon.

The government's case rests heavily on tape recordings of conversations involving Lewis, Boardley, Motlagh, Hechinger official Daniel Russell and an FBI undercover agent, Lewis Smith, who posed as a close friend of Russell. That evidence includes a recording of a meeting between Lewis, Boardley, Russell and Smith at Lewis' home in Northwest Washington in which Lewis says, "If this thing goes down wrong we're all looking at jail."

Lewis' defense lawyer Robert P. Watkins, who spoke only to the Lewis-Boardley jury, said his client does not deny that he made the statements on the tapes but that the key question in the case is "not what was said but why it was said and if it was true."

Watkins said the evidence would show that Lewis was saying what the FBI agent and Russell wanted to hear.

Boardley's lawyer, Robert Mance, warned the same jury that "things are not always what they appear on the surface."

After Beizer made his second opening statement, this time to the Motlagh jury, Motlagh's defense lawyer Jacob A. Stein noted that Motlagh twice denied on the secret tapes that he was paying any money to Lewis or Boardley.