Raised without religion in Maryland, Shannon sought to make a new life for herself as a Jew in Israel.

In a rigorous conversion process, she studied religious law for a year, took a Hebrew name and changed her wardrobe to long skirts and sleeves as dictated by Orthodox Jewish custom. Finally, a panel of rabbis pronounced her Jewish.

But five years later, she and some 40,000 like her have suddenly had their conversions annulled by Israel's Rabbinical High Court. The court says the rabbi who heads a government authority set up to oversee conversions is too liberal in approving them.

The issue, now headed to Israel's Supreme Court, has exposed an intensifying power struggle inside Israel's religious establishment over the age-old question of "who is a Jew." It also threatens to deepen the wedge between Israel and American Jews, who largely follow more liberal schools of Judaism.

While 34-year-old Shannon's Israeli citizenship isn't in jeopardy, the ruling diminishes her religious rights. Many rabbis will no longer oversee basic Jewish rituals for her, such as getting married or receiving a Jewish burial. If she has children, they might not be considered Jewish.

"I'm very worried. I probably will not be able to get married in Israel," she said. "God forbid, if I die, will I be allowed a Jewish burial?"

Shannon was the woman's given name in the small Maryland farm town where she grew up. She asked to withhold her surname and Hebrew first name for fear of antagonizing the rabbis who hold her fate in tourts, said too many people are being converted who aren't genuinely interested in the religion. "Nobody really checked how many of these 300,000 people really wanted to be Jews," Ben-Dahan said.

The decision also has threatened ties with those American Jews who belong to the more liberal Reform and Conservative denominations. The ruling on conversions is seen as another blow to their struggle for recognition in Israel.

"Few crises have so divided Israel from the North American Jewish community," the United Jewish Communities, a U.S. umbrella group that donates hundreds of millions of dollars to Israel each year, wrote to Prime Minister Ehud Olmert in July.

To the group's plea for action, Olmert replied he was "determined" to solve the conversion crisis.

But the same month, Olmert abruptly fired Drukman. He said the law requires the 76-year-old rabbi to retire, but an official said Olmert felt that Drukman's rate of conversions — 3,400 in the three years of his authority's existence — was too slow. The official spoke on condition of anonymity because he was sharing confidential information.

Drukman, speaking to the AP, called the dismissal "foolish and malicious," saying his contract had been renewed only a year earlier.

The Supreme Court is likely to take up within weeks an action brought by Yael, the Danish woman at the heart of the conflict. She converted to marry an Israeli man she met 20 years ago, but during divorce proceedings last year, she acknowledged she did not live by Orthodox rules. The rabbis then invalidated her conversion and everyone else converted by Drukman.

Yael says the rabbis are acting against the spirit of Judaism.

"There is an unwritten law that we should be nice to each other and be human beings, and I always connected this to religion," she said.