Judaism's Conservative branch, which tries to adhere to religious tradition without ignoring modern knowledge, has decided to take a new look at homosexuality, with an influential push from a Los Angeles rabbi-scholar.

Until recently, it seemed unlikely that Conservative Judaism would even consider modifying its approach to sexually active gays and lesbians in light of Jewish law's classification of homosexuality as "an abomination."

Reform Judaism--which together with the Conservative branch dominates U.S. Jewish religious life--approved the ordination of gay rabbis in 1990, but the liberal Reform movement is known for breaks with tradition.

Conservative Judaism has prided itself on devotion to the Torah, or Jewish law, although Orthodox Jewish groups--representing the third branch of Judaism, which is even more rigorously observant--dispute those claims.

A 15-rabbi Commission on Human Sexuality was recently appointed by Conservative leaders to begin a two-year study of homosexual and heterosexual ethical issues--prompted by the recommendations of Rabbi Elliot N. Dorff, provost of the University of Judaism atop Sepulveda Pass.

"Many people in our synagogues are in the middle on this issue and are not sure what to do," Dorff said before leaving last week for Paris, where he chaired the Jewish Law Assn. convention.

"Jewish tradition assumes that homosexuals choose to act that way, but biological studies today raise questions about that," said Dorff, 49, who has taught at the University of Judaism for 21 years and is a member of the new commission.

The Conservative movement's Jewish Law Committee, debating in March whether it was possible in Jewish legal tradition to ordain gay and lesbian rabbis, rejected one rabbi's arguments to allow ordination and produced 12 votes for another rabbi's paper that said the biblical condemnation of homosexuality precludes such a change.

But a third paper presented by Dorff said, among other things, that the context for Jewish law on homosexuality has changed in view of scientific studies and evidence that many Jewish same-sex couples aim at lifetime commitments.

Moreover, Dorff wrote, it was "simply mind-boggling and frankly un-Jewish" to think that God created 10% of humanity "to have sexual drives which cannot be legally expressed under any circumstances." Gay groups and others say studies based on confidential polling establish that about 10% of the population is homosexual.