Like guileless waifs they had sailed, 29 of them in a rickety boat for 11 days, crossing 700 miles of ocean from Haiti to a land where men breathe free air and walk streets paved with gold.

When this contingent of America's "black boat people" innocently hove to on sparkling Miami Beach last weekend, U.S. immigration agents swooped in and arrested them as aliens attempting illegal entry.

They were processed, turned over to Dade County officials and plunged into frightful doubt about their future -- whether this is their land of opportunity or whether they return to prison and persecution in Haiti.

Such scenes have become nearly daily occurrences in south Florida this month. The United States has had its Indochinese refugees, its Cuban refugees, its Soviet Jews and its Hungarian freedom fighters, but never has it had anything like this.

And, because of the Haitians, the thesis that the United States is the ultimate haven and protector for the world's tattered underdogs is facing its most severe test.

In the last week alone, 927 Haitian boat people have been taken into custody. In the last six weeks, more than 2,400 of them -- all black, mostly frightened, illiterate and unskilled peasants -- have landed on Florida shores, looking for work and a chance.

What they have found is no legal work, detention, a hostile U.S. Immigration and Naturalization Service and a sympathetic but outgunned Dade County establishment trying dutifully to deal with a problem that is complexly international and sensitive.

By most reliable estimates, at least 25,000 refugees from poverty and repression in Haiti have come to south Florida in the last decade. Their fate, still very much up in the air, will be decided by federal judges and politicians.

The government insists that they are here for "economic" reasons, which means they cannot stay. The Haitians and their defenders argue they are political refugees, entitled to asylum and the federal benefits that go to political immigrants.

Their defenders include a range of religious and civil rights groups, headed by the National Council of Churches (NCC), and an array of legislators, led by the Congressional Black Caucus, all of whom have called on President Carter to grant the Haitians asylum here.

The official White House position, that the Haitians are here solely for economic reasons, is under heavy attack in a federal court trial of a suit brought by the NCC and civil rights groups.

Testimony this week has indicated that the Duvalier regime in Haiti, contrary to assertions by the Department of State, routinely tortores and imprisons returned boat people as enemies of the impoverished island nation's government.

INS documents introduced in evidence suggested that Washington, seeking not to embarrass President-for-life Jean-Claude Duvalier, has sanctioned a skirting of the usual due-process procedures in handling the Haitians' pleas for asylum.

In its defense, the government is maintaining that INS has merely done its best with existing law, but an overtone in the case is the status of refugees from Castro's Cuba, who are routinely accorded political asylum and federal aid upon reaching here.

For the first time, we are asking a federal judge to extend the equal protection provision of the Constitution to asylum policy, and that it be objective and impartial and not given just to people from countries that are enemies of the United States," said Peter Schey, one of the Haitians' lawyers from the National Center for Immigrants' Rights.

While their lawyers argue the case in U.S. District Court here -- which prevents the INS from deporting them while litigation is pending -- the Haitians live in a melancholy limbo.

Cleared and released by INS, the Haitians have become phantoms in polyglot Miami.Most speak no English, they cannot work legally, they cannot receive federal, social or medical assistance, they cannot receive the cash stipends provided to political refugees. While they wait for a ruling on their fate, their babies are being born as American citizens at a rate of 800 per year at the county's hospital for indigents.

"If this were high enough on the agenda of international problems, it could be resolved easily," said Hall Tennis, an assistant to the Dade County manager. "But as far as Washington is concerned, they are not here." c

The Haitians' presence is straining Dade County's private and public welfare programs, even though Washington has provided some food and health-care money in recent months.

"What we have, meanwhile," Tennis said, "is about 15,000 to 20,000 Haitians out there hustling to stay alive. They are washing dishes, sweeping floors, making furniture in the back room, selling their daughters. The things all desperate people do."

Antoine (not his real name), one of those people, Thursday stood outside a rank and sweaty reception room where about 40 young Haitian men awaited assignment to housing. He talked of the desperation that drove him to spend 11 days in a jury-rigged sailboat to get here.

He is 48, the father of four, a former copper miner from near Port au Prince, who said he had not worked in four years. He and 28 friends pooled resources and sailed to Florida, guided by the sun.

"My parents were supporting me, but it was not fair for the oldest son to stay home and not work. I went three years with my mouth closed. I could not talk about the government. If I did, I could get no job. When you are not part of the government family, you are not allowed to work or do anything," Antonie said through an interpretor.

"I expect to work here and send money back home.I can't tell what will happen to me if I am sent back. But your police and your INS know I am here, and I feel I have no problem now," he said.

Antoine and the other Haitians may stay through the duration of the litigation -- appeals could carry the case on for months -- or if President Carter grants the asylum the Haitians' sympathizers urge.

In a subtle way, this muscular black man was making the point that lawyers Schey, Rick Swartz and Ira Kurzban have tried at length to stress in their suit to Judge James Lawrence King.

The point is that in a society such as Haiti's, where the Duvalier family has reigned for decades and where the average annual income is $225, there is no good way to separate economics from politics, as the INS has attempted to do.

Msgr. Bryan O. Walsh, director of the Catholic Services Bureau here and a veteran worker with refugees from many lands, testified in the trial that he did not believe every Haitian arriving here is entitled to asylum, but, he said, "The vast majority of the Haitians that come here in small boats, risking their lives from considerable personal danger, do so because they have a real fear of persecution."

In Dade County, Walsh said, it has come to be understood that Cubans and Nicaraguans automatically receive political asylum from INS, while Haitians do not -- a suggestion of government racism.

But another witness, former Duvalier presidential guard Daniel Voltaire, himself a boat person, left no doubt about the immigrants' status once they are shipped back to Haiti.

He said that between 1972 and 1979, when he was in the elite guard unit, his orders were to treat all returnees as traitors who had gone abroad to raise money to spy on and work against the Duvalier government.

"Everybody that comes from abroad in a canoquin [traitor]," he said. "My duty is to destroy a canoquin."

Attorney Swartz of Washington said, "My own feeling is that this case has raised serious questions about foreign policy. Haiti is worse than the regimes of Iran and Nicaragua that have been overturned. I just hope that our policies will be made on the basis of facts."

The trial is expected to continue through next week. Saturday, many of the Haitians will attend the funeral of a boat refugee who died this week, and then will march to a rally outside INS headquarters here to hear the Rev. Jesse Jackson and other sympathizers urge the Carter administration to grant the Haitians asylum now.