A bill that passed a crucial committee vote on Thursday would require state agencies to include an optional box for Jewish ethnicity on all demographic data forms, from college applications to public assistance programs. Its passage would make California the first state to officially treat Jewishness as something more than a religion in this fashion — a shift more significant than it might seem.

Scholars of Jewish identity say that it has long posed challenges to American law and public discourse, because Jews have never fit into contemporary conceptual categories. In fact, the challenges — and misconceptions — go back centuries.

“When Jews received the rights of citizenship in European nation states, Jews were forced to think of themselves as a religion,” said Leora Batnitzky, professor of religion at Princeton University and author of “How Judaism Became a Religion.” “But this was always contested from an internal Jewish point of view.”

For its proponents in California, the bill, S.B. 1387, is an attempt to counter this confusion by making clear that “Jewish” means more than religion. Practically speaking, the bill aims to help the state quantify its Jewish population and to enable better data collection for hate crimes tracking and public health purposes — for example, by determining where to promote genetic screenings for diseases common in Jewish communities, or ensuring that antisemitic attacks are not misclassified on reporting forms.

But beyond these concrete impacts, the bill’s backers intend it to accomplish something less tangible: a first step toward acknowledging and demystifying the multifaceted nature of Jewish identity. The purpose of adding the Jewish ethnicity checkbox, they argue, is to break Jews out of the box.

The bill, which heads next to the State Assembly for a vote, is a proposed — and disputed — solution to a very real problem. The complex nature of Jewishness has perplexed the courts, the culture and even the White House. In 2022, Whoopi Goldberg was suspended for two weeks as host of ABC’s “The View” and apologized after she said that the Holocaust was “not about race.” Her statement reflected a popular misconception that Jews have been persecuted in purely religious terms, when in fact, antisemites have long painted Jews as an inferior race.

And it’s not just celebrities who have been flummoxed by Jewish identity. It took until 1987 for American law to determine that Jews might be attacked on nonreligious grounds.

In 1982, a Maryland synagogue was vandalized by white supremacists. In response, the congregation sued the perpetrators under federal civil rights law. Its claims were initially dismissed by the lower courts. But in 1987, in Shaare Tefila v. Cobb, the Supreme Court unanimously reversed those decisions and ruled that Jewish people had the right to sue on grounds of racial discrimination.

Recent presidential administrations have also attempted to thread this needle. Title VI of the Civil Rights Act of 1964 outlaws discrimination in federally funded programs on the basis of race, color or national origin — but not religion.

In 2010, however, the Obama administration interpreted the law as applying to discrimination against Jews and members of other religious groups such as Muslims and Sikhs “when that discrimination is based on the group’s actual or perceived shared ancestry or ethnic characteristics, rather than its members’ religious practice.” In other words, what matters for the purposes of protection is not just how the victims see themselves but how a bigot sees them.

“You don’t have to prove that you look fundamentally different or have some fundamentally different physical characteristic in order to establish that you were subjected to racial discrimination,” explained Matthew Segal, a political science professor at Tufts University.

“It is enough — whether you’re Jewish or Arab or anything else — to show that you were treated differently because someone looked at you that way.”

The California bill was conceived in response to this turbulent context. The bill’s author, State Senator Henry Stern, a Democrat, was motivated by personal experience. He grew up in an engaged Jewish home, but one that was not particularly religious. His father, the actor Daniel Stern, added the improvised line, “Happy Hanukkah, Marv,” in the otherwise Christmas-themed hit “Home Alone 2.”

Later in life, the younger Mr. Stern adopted more traditional Jewish practices, including wearing a yarmulke and observing the sabbath. As he tells it, he knows firsthand that Jewishness is more than religious observance.

“I got picked on in school as a Jew even though I didn’t wear a kipa, I didn’t have a Star of David. But they figured out I was a Jew and they wrote a swastika on the back of my backpack,” he recalled. “I wasn’t a white guy to them. I was a Jew to them.”

The bill has the backing of Jewish California, a large coalition of Jewish groups, as well as the California Federation of Teachers. But not everyone is on board; some progressive Jewish organizations, including Jewish Voice for Peace, have opposed it on various fiscal and ideological grounds.

“Many American Jews, and probably even more in California, are mostly secular, not religiously observant,” the Sacramento chapter of Jewish Voice for Peace wrote in a statement. “If asked offhand, many of us might say we identify as culturally and/or ethnically Jewish. But we vehemently oppose SB 1387 for its wrong-headed oversimplification of identity, one that could well exacerbate antisemitism, among other unintended consequences.”

The bill, the group contends, risks flattening rather than broadening public understanding of Jewishness by compressing Jews into a single ethnicity. (Supporters counter that the box is voluntary and can be checked in conjunction with any other identity boxes.)

“I consider myself a Jew ethnically, but there are many different ethnicities,” David Mandel of Jewish Voice for Peace told the California assembly’s judiciary committee on June 9. “This ill-considered bill, very expensive bill, will not add any useful information for the state and would end up costing millions.”

Mr. Stern is comfortable with the opposition. “That’s what it is to be a Jew, in some ways,” he said. “Being really comfortable with tension, and being comfortable with paradoxes, and understanding that we’re a people, we’re a nation, we’re an ethnicity, we are a religion, too. We don’t fit naturally. And that’s why we’re such a pain.”

Laughing, he added: “It’ll give a lot of grist for people to argue at over kitchen tables, as we have been doing for over 3,000 years.”