When the son of the Brazilian ambassador to the United States shot and seriously wounded a District nightclub bouncer in November 1982 and escaped prosecution because of diplomatic immunity, the State Department expressed regrets to the victim but said no legal action could be taken.

The youth, who fired the gun three times in a scuffle after shouting, "I'm with the Mafia," had been charged with assault once before, according to a Justice Deparment document. Those charges were dropped and he was allowed to remain in Washington -- again on the grounds of diplomatic immunity.

Kenneth W. Skeen, the victim who never fully recovered from his wounds, contends the incident at the old Godfather nightclub might never have occurred if the State Department had followed stricter guidelines in dealing with accused felons who claim diplomatic immunity.

"People hurt people every day, but they usually pay the price," Skeen, who is undergoing psychiatric treatment as a result of the incident, said yesterday. "The government doesn't care what happens to its own people."

Skeen, an unemployed carpenter, is among a handful of witnesses scheduled to testify today in support of a controversial bill introduced by Sen. Jesse A. Helms (R-N.C.) to limit immunity in criminal matters to diplomats and consular officers, while excluding their relatives, dependents and staffs.

"There are 37,000 individuals in this country {in foreign missions and consulates} who are free to commit any crime, no matter how serious, how violent, how heinous, and remain free from prosecution," Helms said in introducing his bill.

Diplomatic immunity has been a perennial problem in Washington, involving everything from traffic and parking violations to assault and rape. Most recently, ABC news desk assistant Stephen Hagan was hospitalized in serious condition after his parked car was struck by a car driven by the ambassador from Papua New Guinea, who police said might have been intoxicated at the time. It is also a major problem in New York, which is headquarters to the United Nations.

"As police officers, we're taught about equal justice under law and that no one is above the law," said Dennis R. Martin, a Saginaw, Mich., deputy sheriff and president of the American Federation of Police who is scheduled to testify today. "For these people to be involved in rape, robbery and drunk driving and not to be prosecuted is wrong."

State Department officials, who are expected to oppose the Helms bill, are sensitive to charges of abuses of diplomatic immunity but have argued that any changes in the current policy could result in retaliation by foreign countries. The department's protocol office stressed in a 1985 statement that diplomatic immunity "does not exempt a diplomatic officer from the obligation of observing local laws and regulations."

However, in the Skeen matter, official State Department correspondence that will be presented at the hearing today appears to suggest that officials were more concerned about minimizing tensions with the Brazilian Embassy than they were about the fact that Skeen's assailant, Antonio da Silveira Jr., went free.

"The guy {da Silveira} had a prior charge, and while Skeen was in a coma, our State Department was over there {at the Brazilian Embassy} consoling and cajoling officials," said journalist Chuck Ashman, an author of "Diplomatic Crime." Ashman obtained the documents under a Freedom of Information request.

In a February 1983 letter to Skeen, Richard Gookin, associate chief of protocol, wrote that "although abuses of diplomatic immunity, such as that which may be involved in this case, cannot be defended, it is not fair to conclude that diplomatic immunity as a concept is not legitimate or that the laws concerning immunity need be changed."

Gookin and other State Department officials were unavailable for comment yesterday.

Peter Christiansen, a recently retired New York City police detective in the Sex Crime Unit, will testify today about the son of a low-ranking attache at the Ghanaian mission who was arrested in 1981 in a series of violent rapes at knife point but then was released because of diplomatic immunity.

Although two of the victims positively identified their alleged assailant, Manuel Ayree, he was released 45 minutes after he was taken to a police station for questioning and later returned to Ghana.

"He looked at me when he left the precinct house and snickered and said, 'I told you I had diplomatic immunity,' " Christiansen said yesterday. "He was looking at the women, too, and laughing. They were crying hysterically."

Steven Goldstein, a New York City real estate salesman, will testify that in April 1985 the then-Mexican ambassador to the United Nations smashed the window of Goldstein's car and pointed a semiautomatic pistol at his head after Goldstein had parked for five minutes in a space reserved for diplomats. No charges were brought against the ambassador.

"Without question, I expected to die," Goldstein recalled yesterday.

The mother of a 16-year-old girl from Northern Virginia, who allegedly was raped at a party by the son of a Saudi Arabian diplomat and the son of a World Bank official in January 1983, has also submitted written testimony for today's hearing.

The son of the World Bank official, who lacked diplomatic immunity, left the country permanently. The Saudi youth, who boasted of his immunity, left the United States then returned and harassed the girl before Saudi officials finally lifted his passport and sent him home, according to the testimony.