One of the neat things about halacha is the way that it's set up to handle changing circumstances. One of the not-so-neat things is that the great poskim of our nation often don't handle changing circumstances well and as a result the implementation of halacha suffers.
One such area of Jewish law is geirus, conversion. Now on the surface it seems pretty cut and dried. There are three elements to the process:
a) Acceptance of the authority of the mitzvos before a qualified Beis Din
b) Circumcison (for males only, please!)
c) Immersion in a mikveh
However, halacha is never that simple. The decision to accept the potential convert into the process of conversion is up to the beis din and there are no ironclad rules there. There is no obligation, for example, to accept just any old candidate who shows up and expresses an interest. Certainly if a secondary gain or underlying agenda is detected the beis din is free to reject the candidate. As horrifying and exclusionary as that sounds to some we must remember that no Gentile has an obligation to convert to Judaism. Turning them away doesn't cause them any loss.
(Frankly the way we're behaving these days it's probably doing them a favour)
Another important factor, tied into the whole agenda issue, is that of the status of Jews in the world. The halacha seems to strongly imply that when we're doing well we're not to accept converts. For example Chazal tell us that during the reigns of David haMelech, a"h, and Shlomo haMelech, a"h, conversions were not allowed. Chazal were concerned that people would want to convert because of the benefits of Jewish citizenship, not out of a pure and altruistic love of God.
The establishment of the State of Israel, along with the integration and achieved equality of Jews in Western countries has raised this issue once again. There are once again perceived benefits to being Jewish, especially in Israel where many people seem to confuse Israeli and Jewish citizenship. Add to that in the West the rising rate of intermarriage, chalilah, and therefore the number of Gentile spouses seeking conversion to imcrease family harmony. Finally throw in the non-observant so-called streams of Judaism and their illegitimate conversion processes and suddenly all sorts of complexities raise their ugly heads.
That's why I think the new Israeli law meant to decentralize conversions will wind up causing more problems than it solves.
Now it's not every day (or month, or year) that I find myself agreeing with Chareidi political positions. In this case, however, they are correct to insist that the central Rabbanut maintains control of the process.
Yes, there are problems with how the Rabbanut does conversions. It has been co-opted by the Chareidi leadership and has imposed neo-Chareidi standards for conversion, presenting them as the authentic mesorah the same way they do in every other area of Jewish life. Conversion candidates are often harassed or made to feel unwelcome. The demands placed on them go beyond what halacha actually expects and the idea that they can be stripped of their Jewish status without so much as a by-your-leave if they fall afoul of even the most minor Chareidi chumrah is against authentic halacha.
But what't the alternative? Decentralizing the conversion process sounds nice and it allowed other Orthodox rabbonim, especially the Religious Zionist and Modern Orthodox ones, into the game. What's more, for the most part those conversions will likely follow the Rabbanut's standards. And yes, that's what the Chareidim are principally objecting to: a break in their monopoly.
On the other hand the Chareidi sector is the largest and most influential of those in the observant world. Pushing through a process their leadership objects to would lead to consequences such as automatic rejection of all non-Chareidi conversions. We already have enough trouble explaining to Reformative converts why they aren't really Jewish and in those cases we have solid halachic ground upon which to stand. How do we explain to an Orthodox candidate that a huge chunk of the Torah observant world rejects him despite his unconditional commitment to Torah and mitzvos?
The answer is to grow the non-Chareidi component of the Orthodox community through outreach and inreach until it becomes the most dominant sector in the Torah world. This won't happen overnight and not without tremendous changes in the outlook of the non-Chareidi Torah leadership but it is the only way to end the bullying without simultaneously defranchising many committed Jews. Until then the process of conversion must, for the sake of the converts and their need to be accepted by all observant Jews, remain centralized.