By MARC LACEY

SAN PEDRO DE MACORIS, Dominican Republic — Two obsessions define this country: baseball and Haiti. Ángel Luis Joseph, a teenage outfielder with a hot bat, is caught between Dominicans’ devotion to the one and disdain for the other.

So many major leaguers have emerged from this sugar town that agents keep an eye on even pint-size players with potential. Ángel, 17, was only a lanky grade school boy when his coach noticed he showed all the signs of becoming a standout. Before long, the San Francisco Giants came calling with a $350,000 offer, he said.

But then politics interfered with his dream. To obtain a visa to the United States, Ángel went to a local government office to get a copy of his birth certificate. Little did he know that the Dominican government had recently begun a crackdown on the children of Haitian immigrants, even those like him who have lived their whole lives in the Dominican Republic.

“If your last name is weird, they won’t give you your documents,” he said. “Same thing if your skin is dark like mine.”

Ángel’s request for his birth record was denied, prompting the Giants to withdraw the offer.

His parents, like hundreds of thousands of others, moved from Haiti to the Dominican Republic in the 1970s to work in the sugar cane fields. Their children were born in the Dominican Republic, grew up here and became, in their eyes at least, full-fledged Dominicans. They speak Spanish, dance merengue and play “pelota,” the popular name for the Dominican pastime baseball.

“They don’t play baseball in Haiti,” said Melanie Teff, who has studied the issue for Refugees International, an advocacy group in Washington. “That shows how Dominican this guy and many people like him are.”

The government does not necessarily agree, and Ángel awaits a ruling on his appeal for access to his Dominican birth record.

The issue arose with a fury several years ago when advocates took the government to the Inter-American Court of Human Rights, whose jurisdiction the Dominican Republic acknowledges, to protest the denial of birth certificates to two ethnic Haitian children.

While the case was in process, the government changed its migration law in 2004 to specifically exclude the offspring of Haitian migrants from citizenship. The Dominican Constitution grants citizenship to those born on Dominican soil, except the children of diplomats and those “in transit.” That has long meant that the children of immigrants, no matter their legal status, gained Dominican citizenship.

After the international court ruled against the Dominican government in 2005, ordering that damages be paid to the two children, the Dominican Supreme Court said that Haitian workers were considered “in transit” and that their children were therefore Haitian, not Dominican.

Last spring, the government agency in charge of identity documents, the Joint Electoral Council, issued a memorandum telling its employees to watch for the offspring of foreigners trying to identify themselves as Dominican. It now hangs at every clerk’s office and is shown to people thought to have Haitian blood.

“The issue of Haiti has become very combustible in the Dominican context,” said Daniel Erikson, director of Caribbean programs at the Inter-American Dialogue, a research group in Washington. “You have a deep resentment of Haiti, and that’s driving these responses that don’t reflect favorably on the country.”

Government officials point out the strain that poor illegal immigrants from Haiti put on the Dominican Republic. The two countries share the island of Hispaniola but have vastly different levels of development.

Of course, Haitians contribute, too. They have long worked in the jobs Dominicans did not want to do, mostly cutting cane on plantations that supply sugar to the United States. The government has not just known of their presence for decades but has in some cases encouraged their arrival.

The Dominican government says the new crackdown is a security matter, aimed at wiping out fraud. And in some cases over the years, young Haitians who had crossed the border illegally claimed to have been born on the Dominican side.

But opponents accuse the government of applying its 2004 law retroactively, which they call an illegal practice that has longstanding societal animosity against Haitians at its heart.

“The racist beliefs of some are being used to twist our laws,” said Cristóbal Rodríguez Gómez, a Dominican constitutional law professor at Ibero-American University, who is acting as counsel for another descendant of Haitians who lacks documents. “This is a crime, a monstrous crime.”

In a recent report, two United Nations experts found “a profound and entrenched problem of racism and discrimination” in the Dominican Republic, mostly affecting people of Haitian origin. The report said Haitians and their descendants face “extreme vulnerability, unjustified deportations, racial discrimination, and are denied the full enjoyment of their human rights.”

The Dominican government rejected the conclusions, portraying the relationship between the neighbors as one of solidarity.

Ángel is one of many who find their lives in limbo under the new rules. Emildo Bueno Oguis, 33, a college student who recently married an American woman, could not get his birth certificate either and therefore cannot apply to the American Embassy for residency to join her in Florida.

Mr. Oguis, whom Mr. Rodríguez represents, challenged the government’s decision in court, accusing the council of denying his rights. But his claim was rejected, despite the fact that he had previously been issued a Dominican identity card and a Dominican passport.

Confusing the matter, a lower court judge ruled in favor of another descendant of Haitian immigrants, Nuny Angra Luis, who had been denied her birth certificate. That decision was announced the same week in April as the other, diametrically opposed ruling.

Demetrio F. Francisco de Los Santos, a government lawyer, dismisses the notion that anyone’s rights are being violated. Descendants of Haitians, he argues in court documents, can simply go to the nearest Haitian consulate for their documents.

While Haitian law does grant citizenship to the offspring of Haitians, the issue is complex. Ángel’s parents would have to prove they are Haitian for him to get citizenship in Haiti, a country which he has never visited.

While some are indignant about the Dominican crackdown, Ángel seems surprisingly calm.

Before a recent practice, in which he flagged fly balls and then fired them into the infield, Ángel said his mother could not sleep after he lost the Giants contract. (“Ángel Luis Joseph is one of a number of players in the Dominican that clubs are finding do not have the proper paperwork to prove their identity or age,” the Giants said in a statement, indicating that the team had been forced to look for someone else.)

Ángel may have another shot. The Cleveland Indians have come calling, he said, visiting the humble shack that he shares with his parents and seven siblings just outside a sugarcane field.

The Indians’ offer was about a third of that put forward by the Giants, but still a windfall for a boy from a batey, the name for the workers’ camps that grow up around sugar cane plantations.

But while he awaits a ruling, he acknowledges worrying that he will see his dream disappear a second time.

“God wants me to be a baseball player — that I know,” he said. What he does not know is whether the Dominican Republic, the country he considers himself from, agrees.