Ignacio Ruiz De Armas is one of 1,800 Cubans who have spent more than a year in a federal penitentiary without having been charged with a crime in this country.

He first went to prison in Cuba. He hated life under President Fidel Castro so he resisted, he said. He refused to join the army. He distributed anti-Castro leaflets. Then, he tried to escape the island in a small boat and was caught.

He told his story to U.S. immigration officials after arriving in June, 1980, with "Freedom Flotilla" refugees and wound up behind bars in Atlanta's federal penitentiary with 1,800 other Cubans who have lived in legal limbo for more than a year.

Castro won't take them back, and the U.S. government won't let them out because it says they are dangerous criminals. Tyrus Minnox, district director of the Immigration and Naturalization Service here, asserts that the Cubans have been detained because back home they committed "crimes so base and violent that they should not be allowed to associate in normal society."

Indeed, some are hard-core ex-cons from Cuba: murderers, rapists and burglars. Several hundred are said to be mentally ill. But as many as 1,000 are believed to be petty thieves, political prisoners, victims of red tape and men like Ruiz De Armas, whose Cuban "crimes" would be considered minor offenses under American law, according to lawyers for the Cubans and the U.S. Catholic Conference, which has resettled thousands of Cuban refugees and maintains detailed files on the detainees at its prison office.

Ruiz De Armas is an ex-barber whose immigration records show only that he went to prison because he stole a boat -- not that he stole a boat to escape Castro, according to his lawyers.

"Something was lost in translation," Ruiz De Armas said in a prison interview. He wants to live in Venezuela if released. He no longer nurtures his American dream.

"I have been disillusioned," he said. "I thought I would find democracy here, but I have found a monster like Castro's government, with arbitrary, inhuman laws. After what I've been through, I can no longer tell the difference between Cuba and America."

The Justice Department has kept the Cubans locked up because it hasn't yet figured out what to do with them. Some have gone 14 months without an administrative hearing, attorneys for the INS have conceded in court. Officials say they are being held because their convictions in Cuba make them legally excludable on grounds of "moral turpitude" or national security.

But 319 detainees, as they are called, remain in prison only because they lack U.S. entry papers. Lawyers contend they are being held arbitrarily and emphasize that some 125,000 Cubans who arrived without papers have been released from resettlement centers. Several hundred remain behind concertina wire at Ft. Chaffee, Ark.

Many Cubans have spent more time behind bars in America than they spent in prison back home, where they were convicted. Few have been formally charged with crimes in this country. And while they have awaited their fate, four men have been murdered in the tension-packed federal penitentiary, its 8-foot thick concrete walls built to hold the likes of Al Capone.

"You cannot imprison people if they have not committed a crime," said Gene Guerrero of the American Civil Liberties Union. "But that's what the government has done."

Federal courts in Denver and Kansas have ruled that deportable aliens have constitutional rights once they are admitted to this country, even temporarily, and those held in custody for more than a few months must be released because such detention amounts to imprisonment.

U.S. District Court Judge Marvin Shoob, in response to a class action suit against the Justice Department, has indicated he will free hundreds of Cubans unless U.S. attorneys representing the INS can show in court here Monday why the 319 Cubans imprisoned only because they lacked entry papers would be a danger to society. Shoob has already freed two Cubans detained for lacking such papers.

"Why should these people just stay in jail week after week and month after month?" he asked in court last month, when he refused to wait any longer for the government to make a "policy decision" about the Cubans. He criticized the Justice Department's plan to set up a review panel, scheduled to start examining each Cuban's case Aug. 24, as too cumbersome and too slow.

The Justice Department wants the Cubans held until officials "can weed out the good ones from the bad ones," said Assistant U.S. Attorney Robert Castelanni. "If they were all bad, we wouldn't have any review. The government is not an ogre."

The government has been slowed, he argues, by changing administrations, subsequent shifts in immigration policy, scanty files on the detainees and poor cooperation from Castro for requested documentation on the men. It needs more time, he said.

Last year, the INS approved 173 men for release -- those held for offenses so minor (or no offenses at all) as to represent little threat to society -- and some were freed before Attorney General William French Smith halted their release pending his policy review.

Among the detainees here:

Lazaro Batista-Padron, a Havana University student who used his cousin's prison papers to join the boat exodus. He never told immigration authorities in Key West, Fla., his real identity, he said, because he feared he would be thrown in jail "for impersonating someone else." He has spent 17 months in prison here, and awaits the arrival of his birth certificate to establish his identity.

Felix Preval Peralta, who said he slept with a girl, then refused to marry her. The woman's parents accused him of rape.

Jose Luis Alonso Herrera, who reportedly stole a battery and a sack of sugar.

Roberto Villamil Drake, who said he looked the other way when a friend, desperate to pay his mother's hospital bills, helped himself to $600 from the cash box in the bar where he worked.

Francisco Joya Rosales, who said he was identified as a communist by two refugees at a resettlement camp, put in a special "pinko" category and placed in prison, even though he believes that Castro runs a "bad, oppressive system." The U.S. government approved his visa request two years ago. He was waiting for Cuba's permission to leave when he learned about the boatlift and decided to get out fast.

"They're not all criminals, but there are enough among them to be concerned about releasing them all," Castelanni said. "We're trying to expedite the cases as reasonably as possible, balancing the public interest against the interest of the detainees."

Minor offenders sleep dormitory-style in the prison's crowded, steamy basement, watching soap operas they don't understand, playing cards, and awaiting news. Many work in menial prison jobs for 39 to 54 cents an hour.

The Cubans contend in a separate lawsuit brought in Atlanta that prison guards have brutalized them. Acting Warden William Noonan counters that his men have been attacked. Several guards have been disciplined.

After Judge Shoob rules Monday on the class action on behalf of the 319 Cubans imprisoned for having no entry papers, he plans to consider other categories of detainees: those convicted of a single misdemeanor in Cuba, others with multiple misdemeanor convictions, those sentenced by Castro's revolutionary tribunals, less serious felony cases, those convicted of serious crimes such as murder and rape and the mentally disturbed.

"It violates every basic principle of our democracy to keep a man in maximum security prison with no evidence he has committed a non-political crime," Shoob declared in court.

But he was quick to emphasize that he was just "as determined" to "keep people incarcerated who are dangerous."

What bothers the judge is that the Reagan administration may be dilly-dallying over the Cubans because the issue is politically hot. "I sense that there are a lot of people out there in the federal penitentiary who ought to be released," said Shoob. "And I'm afraid that nobody in Washington is making those decisions, that nobody wants to make those decisions."