Prime Minister Indira Gandhi's son Sanjav and one of their political allies from her authoritarian emergency rule were acquitted by the Indian Supreme Court today of charges that they destroyed a movie satirizing the Indian political system.

If the Supreme Court had upheld the lower court convictions, Sanjay Gandhi, 33, and former information minister V. K. Shukla could have been sentenced to jail terms of two years and ordered to pay heavy fines.

The court's decision was expected since the prosecutor, appointed by Gandhi soon after she won election in January, spent only 15 minutes responding to three months of defense arguments before the three-judge panel.

In the three months since Gandhi's reeletion, many of the charges filed against her and her allies for alleged excesses during the 20-month emergency period have been dismissed speedily by Indian courts.

The court said in its opinion that the prosecution had failed to prove that a conspiracy existed between Sanjay Gandhi and Shukla to destroy the satirical film, "Kissa Kursi Ka" -- "The Story of the Throne" -- film was supposed to touch on Sanjay Gandhi's controversial Maruti car plant.

"I congratulate the accused, but I wish I could congratulate the judiciary," commented Ram Jethmalani, who was replaced as prosecutor after Gandhi took office.

While neither Gandhi nor Sanjay had any comment tonight, the general secretary of their political party, the All India Congress Committee-I (for Indira), called the verdict "a triumph of truth over falsehood."

The Gandhis have insisted all along that the scores of criminal cases against them and their allies as a result of the emergency excesses were part a campaign by political foes to vilify them.

The "Kissa Kursi Ka" case differed from the others against Gandhi and her allies in that it was only one in which her closest associates were convicted by a trial and sentence to jail.

Sanjay Gandhi still faes criminal charges in at least six more cases, including one of assault and battery on a police officer during a riot last May.

Besides the changing of prosecutors in midstream, the "Kissa Kursi Ka" case was filled with legal complexities.

Amrit Nahata, the filmmaker whose complaint started the investigation, recanted some of his testimony against Sanjay Gandhi and Shukla in an affidavit filed during the December election campaign.

He said he had been put up to give false testimony by Charan Singh, the caretaker prime minister and one of the prime movers in the efforts to the Gandhi's. Nahata was later given a place on Gandhi's winning Congress-I ticket.

The film was made in early 1975, before Gandhi declared her emergency rule. It was controversial from the start, with the country's board of censors split over whether the film should be shown.

After the emergency was imposed in June 1975, Shukla became information minister and ordered the film seized. The Supreme Court ordered Nahata to turn over the film to the government. But the government said the film had mysteriously disappeared when ordered to produce it a few months later for a Supreme Court viewing.

After the Gandhi government was defeated in elections in March 1977, Nahata asked the new administration to investigate the loss of the film.

According to police records, investigators found evidence at Sanjay Gandhi's Maruti car factory that the film had been burned there in November 1975.

The trial of Sanjay Gandhi and Shukla before Delhi's sessions court took 11 months. They were convicted and sentenced in February 1979, while Indira Gandhi was out of power. There was a 6,500-page record, taking up 29 volumes.