Was it apple cider - or was it Tuaca?

That is one of the key questions before the D.C. Alcoholic Beverage Control Board as it deliberates the fate of Guncher's, a popular Georgetown eating and drinking spot.

Apple cider is what Louis J. Calomaris, owner of Guncher's, says was served to a group of freshman girls from Marymount College on the evening of Sept. 9, 1976 - at Guncher's second-anniversary party.

But Tuaca, a cinammon-scented liqueur, is what three Marymount students told the ABC Board they wree served that night - enough Tuaca to put several students in the college infirmary, and one in the intensive-care unit at Arlington Hospital.

"It was a very busy night," recalled Linda McMahon, dean of students at Bridge in Arlington. "Nothing like that has ever happened before or since," McMahon said, although she later added, "We fight a constant battle with this sort of thing."

Nearly 1 1/2 years after that night, the ABC Board is weighing whether to find Guncher's guilty of serving hard liquor to persons under 21. Guncher's could face a stiff sentence, according to an official handling the case - either a long suspension or perhaps outright revocation of its liquor license.

The Guncher's case is anything but a run-of-the-mill affair for the city's three-man, part-time ABC Board. Its unusual features include:

The prosecutor's accusation that Guncher's, beyond serving liquor to underage patrons, served it in bountiful quantities free and distributed "advertisements" (Calomaris calls them "invitations") at Marymount, knowing most of the students are 18 or 19 years old.

A year's lapse between the night of the party and the bringing of charges by the ABC Board, a delay sharply criticized by the defense, the prosecution and even one member of the board itself.

The related filing of a $15 million lawsuit by a Marymoung student who left Guncher's that night with an off-duty bartender and was later delivered, unconscious, to Marymount, according to Dean McMahon.

And the extraordinary interest taken in the case by city administrator Julian Dugas, who decided to attend an ABC Board hearing for the first time in nearly three years. He has left handling ABC Board business to his two colleagues, Arthur W. Jackson and James W. Hill.

Dugas' participation enabled him to cast the deciding vote, with Hill and against Jackson, to deny a motion for dismissal of the charges based on delay. But attorneys for Guncher's have filed a motion to disquality Dugas, claiming he was never formally reappointed to the ABC Board after an initial term that expired in 1975.

The split between Hill and Jackson was described as unusual by an official who has attended countless ABC Board hearings. Other board members and staff were uncomfortable, the official added, because of Jackson's practice of driving to work with Louis N. Nichols, a neighbor who happens also to be Guncher's attorney.

To make matters more complicated, Nichols is a former member of the ABC Board who resigned 12 years ago after being observed drinking after hours in a Georgetown bar.

During three hearings on the Guncher's case, Nichols pressed the board to explain the delay in bringing charges. The only explanation offered was a shortage of staff. D.C. police investigators had completed their investigation within weeks of the incident, said Sgt. Dennis Martin of the morals division.

After the Marymount students and McMahon had testified, a group of Guncher's employees insisted to the ABC board that they had not violated the law. "I made it my business," said Calomaris, "to make sure that no Tuaca was serve" to anyone under 21.

A Guncher's doorman testified that some of the 15 to 20 Marymount students had left Guncher's early, talking about visiting other Georgetown bars, and had later returned to use Guncher's direct phone line to Arlington's Red Top Cag Co.

Potentially the most damaging prosecution witness eventually decided not to testify. She is Teresa Lynn Phelan, the student who later filed the $15 million lawsuit. Only a few days after arriving at Marymount from her home in New Jersey, Phelan attended the Guncher's anniversary party and, according to fellow students, left at about 11 p.m. with bartender Michael Hodgon, whom she had met there.

When Phelan was hospitalized early next morning, "the alcohol contained in her system was so high that we're lucky she's still alive," said McMahon.

What happened in between is unclear. Although Phelan's lawsuit alleges that she was assaulted, it includes no details and no criminal charges have been filed.

Hodgedon, who has dated Susan Ford, daughter of the former president, denies any impropriety. In testimony before the ABC Board, Hodgedon supported Calomaris' assertion that the Marymount students had been given cider rather than Tuaca. They might have been told they were getting Tuaca, Hodgdon explained, but that was just to humor them.

The ABC Board's charges make no mention of Phelan or an assault. But board members asked several witnesses if they had seen "anything unusual." The witnesses said they had not. And before Hodgdon began his testimony, Dugas, without explanation, referred to him as a "critical witness."

Calomaris and his attorneys regarded these references as indications that Gunchers was being tried for more than allegedly serving liquor to underage patrons. Dugas, however, told The Washington Post that he had no knowledge of any facts beyond what was on the record.

A police investigator who has worked regularly with the ABC Board described Guncher's as "worse than some" Georgetown bars, but "better than most." Guncher's serves more food than many competitors, he said. D.C. law requires that all liquor-licensed establishments derive their "chief source of revenue' from sale of food, a requirement that is widely ignored.

The investigator agreed with Calomaris that the board's handling of Guncher's case has been uncharasteristic. Some more serious allegations against other bars and restaurants have gone unprosecuted, said the investigator. He added that the ABC Board has dropped a number of cases because of delays comparable to the delay in the Guncher's case.

The usual procedure when a bar is accused of selling liquor to minors, said the investigator, is for police to make a series of inspections, hoping to establish a pattern of lllegal conduct.

Mary E. Reed, deputy staff director for the ABC Board, agreed that she was unable to remember another case in which police or ABC investigators had not observed underage patrons being served. But she said the Guncher's case was extraordinary because the alleged violations had occurred during an invitational party rather than on a normal business night.

Several Guncher's regulaas, including Cissy Baker, daugther of Sen. Howard Baker (R-Tenn.), have told The Washington Post that Guncher's routinely checks ages of student customers. Baker, president of the student body at Mount Vernon College, said she had turned 21 in March 1977, and "not until that date did they serve me any hard liquor."

Every fall, Baker added, Guncher's provides volunteers and a truck to help incoming Mount Vernon students move belongings into dormitories, "It's a big brother, little sister relationship," she said.