In what may become known as one of the most bizarre trials in American history, an American court has been convened by the U.S. ambassador in Berlin to try two East Germans for violating West German laws against aircraft hijacking.

The rare procedure is authorized under the United States' seldom-used authority as occupying power in West Berlin and will take place because the West German government is reluctant to prosecute persons who flee from East Germany, as did the accused hijackers.

Ambassador Walter S. Stoessel Jr. assembled an all-star cast for the trial. The judge is Herbert J. Stern of the U.S. District Court in Newark who gained fame a decade ago while prosecuting the Mafia and corrupt politicians in New Jersey. At 43, he is the second youngest federal judge, an important factor in a case that involves the physical strain of frequent trips to Berlin.

Two crack defense attorneys that few Americans or Germans could afford have been assigned the East Germans. They are Judah Best who represented Spiro T. Agnew during the plea bargaining that led to his resignation as vice president and Bernard Hellring who once defended the former Newark mayor, Hugh J. Addonizo, in a case that Stern prosecuted.

As prosecutor, Roger Adelman was taken from his normal job in the criminal division of the U.S. Attorney's Office here.

"This is going to be a real trial, not a circus. We are going to show the best of American criminal justice. There will be no shortcuts," said Bruno A. Ristau, a Justice Department official who has been named clerk-marshal for the court.

The first major issue before the court is whether the two defendants -- Hans Detlef Alexander Tiede, 31, and Ingrid Ruske, 32 -- are entitled to a jury trial, which Best said, "We are going to demand."

Stern has asked the lawyers to submit legal arguments on the constitutional question of just what are the rights of two East Germans charged with crimes against West Germany being tried in an American court formed as a result of authority given to any occupying power.

That leaves out the practical problem of who could be selected as a jury of the defendants' peers. Should the jury be Americans living in Berlin? Or Germans from West Berlin? Or Germans from East Berlin? Or Germans picked from the entire city?

Adding to the unique nature of the case, the trial will be conducted under the same rules governing federal court trials in this country. But any appeal of the court's decision will be taken to the ambassador, not to an American or German appeals court.

Ristau, head of the Justice Department's foreign litigation unit, has been faced with the task of creating a full fledged federal court where none now exists. The U.S. has not convened a court in Germany under its occupation powers since 1955 when West Germany formed its own court system to replace one set up by U.S. occupation forces.

Ristau has pulled together a team of translators so the defendants, who speak only German, can understand the judges and lawyers, who speak only English.

These translators, thought fluent in English, are already having trouble with American legal jargon and finer technical constitutional points, according to one American lawyer who attended the preliminary hearing, which was held last week in a specially built courtroom at Tempelhof Air Base in the American sector of Berlin.

Ristau has found stenotypists to keep the trial record, which will be publicly available here and in Berlin, and an impartial expert to advise the judge on the German laws the defendants are charged with breaking. In addition, bilingual German lawyers have been hired to assist Adelman, Best and Hellring.

The American defense attorneys are taking the case for $20 an hour for office work and $30 an hour for appearing in court -- a fraction of what they normally charge. These fees are the same amount the U.S. government pays lawyers assigned by federal judges to represent defendants who can't afford their own attorneys.

By contrast, the going hourly rate for top Washington trial attorneys is $100 and up.

Poland -- which had three official observers at the preliminary hearing -- and East Germany have demanded the return of Tiede and Ruske so they can face charges there.

The fact that the Polish airliner landed last August in the American sector of Berlin gave the West Germans a perfect out. They could allow the United States -- still an occupying power of that divided city with the right to veto local laws much as the U.S. Congress can veto laws by the D.C. City Council -- to step in.

Since the trial is being conducted by the United States as an occupying power, the costs are borne by the West German government -- which leads to another strange twist.

Just as the U.S. government insists that federal employes fly American airlines while on official business, the Germans who are footing the bill for this case have insisted that the Americans taking part use the German airline, Lufthansa. In addition, their expenses are reimbursed in deutchmarks.