Noah Millman provides a lot of background and contextual information  that helps an interested outsider make sense of the recent decision by the ruling body of Conservative Judaism to endorse gay marriage. Read the whole thing, if this topic interests you. Excerpt:
The formal structural difference between how Orthodox and Conservative Judaism look at halacha is that from an Orthodox perspective, halacha doesn’t get revised, though it does develop, organically, in a kind of common law fashion, with individual rabbis making rulings on new issues based on established precedent and their own view of how this precedent should be applied. Whether those rulings, in turn, are accepted by other rabbis is up to them.
Conservative Judaism, by contrast, has a central body responsible for deciding what thehalacha is – the Rabbinical Assembly. It decides which interpretations of the law are valid (and sometimes it decides that multiple interpretations are valid) and which are not. And it has the power to revise the law as needed, either by rejecting an earlier authoritative rabbinic interpretation in favor of a novel interpretation of scripture, or by (in an extraordinary case) outright “correction” of scripture (on the basis of some higher principle with its own scriptural warrant).
I’m not going to go into the formal justifications the RA has for asserting this power – they have articulated justifications which, needless to say, are not accepted by any Orthodox rabbi I’m aware of. The point is: the halacha as formally understood by the Conservative movement doesn’t work quite the same way as the halacha as understood by Orthodox rabbis. The former is centralized, the latter de-centralized; the former is subject to formal revision, the latter only to common-law-style development.
I suspect that Dreher thinks it isn’t tenable to proclaim fidelity to a tradition that can be radically revised. But I don’t think that’s the case.
Well, not quite. I believe that an authoritative body making an authoritative change in the tradition is more or less on solid ground, but that there is a big theological problem when the proposed change is radically (= at the root) discontinuous with the past tradition, such that it fundamentally contradicts what was taught before. The ancient Christian belief that there is no salvation outside the Church  has been interpreted in a number of ways over the centuries. In 1302, Pope Boniface VIII (in)famously said: “We declare, say, define, and pronounce that it is absolutely necessary for the salvation of every human creature to be subject to the Roman Pontiff.”
Pius IX restated this understanding as late as the 19th century: “For, it must be held by faith that outside the Apostolic Roman Church, no one can be saved; that this is the only ark of salvation; that he who shall not have entered therein will perish in the flood; but, on the other hand, it is necessary to hold for certain that they who labor in ignorance of the true religion, if this ignorance is invincible, will not be held guilty of this in the eyes of God.”
The Catholic Church no longer teaches that. The Church, in its official teaching, says that salvation does come to the world through the Roman church, but if someone sincerely does not understand that, and does his best to obey God within the limits of his understanding, he may be (not “will be,” but may be) saved, even though he is not a Catholic. This strikes me as a humane and reasonable interpretation. Whether or not it can be reconciled with what Boniface VIII authoritatively proclaimed is another question. As I said — and as reader Geoff Guth asserted in another thread — the trick is for traditions to maintain enough flexibility to change as deemed necessary, while making it appear that there has been no radical change at all. If it was true for centuries that to be saved, one had to be a Roman Catholic, and now that’s not true, one may rightfully wonder whether the Church’s authority can be trusted, if it can be so radically revised.
That was the source of my original bafflement with the Conservative rabbis’ decision. Expanding the understanding of marriage to include same-sex unions struck me, an outsider to Judaism, as a shatteringly radical departure from Jewish tradition. Noah explains why Conservative Judaism situates itself with regard to halacha, or Jewish law, in a fashion that makes accepting same-sex marriage understandable. In other words, if I understand Noah’s point, the break with Jewish tradition that made such a move possible had already been made a long time ago. Whether or not that was a theologically justifiable break is another question.
In any case, Noah’s post makes it clear why one should be extremely careful applying the standards of understanding of one’s own religious tradition to different religious traditions. I see this most often on this blog with readers who are surprised and offended that the Catholic Church doesn’t understand itself as a Protestant body, and therefore acts like the Catholic Church instead of the Episcopal Church.