Trial began here this week for more than 7,000 prisoners charged with war crimes, corruption and abuse of power under the ousted government of dictator Anastasio Somoza.

Among the first nine prisoners brought before specially created tribunals Monday is Jose Antonio Vasquez, a lieutenant in Somoza's National Guard. The government has asked the maximum penalty, 30 years in prison, for Vasquez on charges of ordering bombing raids on civilian homes during last summer's civil war.

Vasquez and the others are allowed to choose their own defense attorneys. As part of an effort by the new Sandinista government to prove it is scrupulously fair, court-appointed lawyers will be named to defend those without representation.

The government is aware that the trials will be followed closely in Washington and other capitals as demonstrations of the seriousness of the government's pledge to protect human rights.

The trials are being held in three luxurious mansions abandoned by fleeing Somoza supporters. At a swearing-in ceremony last week, 36 members of the civilian tribunals -- most of them students and workers -- raised their right hands and pledged. "In the name of the heroes and martyrs fallen in the fight for the liberation of Nicaragua," to serve "the interests of the people."

The ruling junta has also named one lawyer or senior law student to each three-person tribunal. "It is an example of revolutionary justice, Nicaraguan justice and Sandinista justice that all these trials will be civilians," junta member Violeta Chamorro said last week.

Protection of the rights of the prisoner, most of whom are former Somoza soldiers, will not be easy in a country where the words "National Guard" usually are preceded by the adjective "genocidal," and reports of murders, torture and other abuses by the guard are aired daily by the media.

When it was announced that the 36 prisoners under age 16 would not be put on trial but remanded to juvenile authorities for rehabilitation, a group of mothers of young people killed during last summer's insurrection against Somoza protested.

At a press conference, one of the women said she had been forced to watch while her young son was tortured to death. The mothers said many of the young prisoners were members of an elite National Guard unit that "specialized in torture."

On the other hand, Jose Esteban Gonzalez of the Permanent Commission of Human Rights has said he believes as many as half the prisoners should not be put on trial at all. Gonzalez, a leader of the Social Christian Party, also said he believes there may be as many as 10,000 prisoners.

The tribunal system is patterned after traditional criminal trials here, which are heard by seven-member juries instructed to decide "according to their consciences." Several lawyers said these juries in the past sometimes released Sandinistas accused of bank robberies or attacks on the National Guard.

Nora Astorga, a lawyer and former guerrilla, has named special prosecutor. She said she will study the evidence submitted by Interior Ministry investigatory and order the release of prisoners when there is insufficient evidence.

Astorga, 32, is well known here because of her involvement in the assasination in 1978 of a high-ranking general whose body was found in her bedroom wrapped in a Sandinista flag.

The prosecutor and lawyer Mario Mejia, who is coordinating the trials, have announced that all prisoners will be tried under the existing penal code for crimes such as murder, rape, torture, robbery and fraud. The maximum 30-year penalty has led some Nicaraguans to call the trials "Nurembergs without the gallows."

Each case is to be decided within 28 days or the prisoner will automatically be released, Mejia said. Three of the 12 tricunals will hear appeals. The tribunals work from 7 a.m. to 7:30 p.m. and hear several cases each day. The junta hopes to have all the trials finished in six months.

Most of the proceedings are written buy reporters are permitted to hear the limited oral testimony and read all documents. The trials are not open to the public.

A special decree has deprived the prisoners of certain rights, such as habeas corpus, to get out of jail while waiting for formal charges of trial. The government has defended this by saying that it would be difficult to process such a large number of people through the regular procedures.