quote:

But if the Bais Yosef is the Mara D'asrah of Eretz yisrael, wouldn't it be Lo Sisgadadu to hold onto your old traditions? Obviously, most poskim would concur that there is no one "Morah D'Asrah" and it's a Makom with many "Batai Dinim." It could be argued that the Talmidai HaGra, who the Yerushalmis were from, would Kovea that the Gra would be the Morah D'Asrah (thus much of Minhag Eretz Yisrael is based after the Gra's opinion.)

In the past it was common that when a person left his home and moved somewhere else he would take on the custom of the new place.

The TUR based on Talmud Bavli Mashechet Chulin 18b says:

" A person who leaves his place and settles in another place he is to follow the minhag of the place where he wishes to settle in. If he intends to settle in the new place he should follow the minhag of that place whether lechumra (more stringent) or lekula (more lenient)"

There is no source in the Gmara for the situation today where you take your home custom with you to a new place.

The Rambam in Hilchot Avoda Zara chapter 12 says
on lo Tithgodedu:
"This commandment also includes a prohibition against there being two courts which follow different customs in a single city, since this can cause great strife ... 'Do not separate into various different groupings"
(from Rav Eliyahu Touger's translation)

The issue of two batei dinim in once city is discussed in Talmud Bavli Yevamot 14a
see http://www.dafyomi.co.il/yevamos/insites/ye-dt-014.htm

Abaye's opinion is that there can't be two batei dinim in once city.
Rava's opinion is that it is ok to have two batei dinim in once city.

In most cases we follow Ravva's opnion and almost all poskim have accepted Ravva's opinion in this case. Some like the Kesef Mishne tried to explain that even the Rambam did not mean exactly what he said. Others like the Radbaz however explained the Rambam's reasoning for accepting Abye's opinion.

Anyways Rav Chaim is 100% correct that almost all of the poskim today accepted Ravva's opinion explain that today we have a situation with many batei dinim.

While this may be 100% valid, is it ideal?

The reason we don't psak based on the Tur regarding one moving to another place is that entire kehiloth moved and not just a single person.

It is interesting to analyze the situation that existed when the Kehiloth moved to Israel not too long ago.

When Ashkenazi, and Spharadi Kehiloth came to Israel they were clearly separate kehiloth.
They often lived in separate neighborhoods, went to different schools, different yeshivas. It is well known that Ashkenazi Yeshivoth would not take Spharadi students. It wouldn't be very accepted at the time for an Ashkenazi to marry a Spharadi.
Given this situation it is clear why the Ashkenazi Kehiloth weren't going to simply drop their minhagim and take on the Beith Yosef.

So the jusftification was that it was like having 2 Batei Dinim in once city.
As explained above this was valid as it was accepted by almost all.

The situation today is very different in Israel and having many batein dinim causes many problems.

Today the different Kehiloth aren't really separate kehiloth anymore. We live together, we go to school together, go to the same yeshivoth, we daven together at work and even in the comunity. It is very common and accepted for ashkenazi sfaradi and yemanites to marry each other.

We also don't really have many batei dinim. It is actually a pilpul on the idea. Very often today ashkenazim and sfaradim will consult the same Rav. The Rav will give different answers to each based on their edah.

Now why am I saying that it is problematic?

Well the result today is that we have 100 badatzim to give Hechsherim. Rav Ovadia Yosef says in one of his shiurim that we have so many Hechsherim today it is all just business. The reason we havve so many badatzim is that we have so many batei dinim and there is no unified accepted set of Kashruth laws.


Now is it a good thing that you can't eat freely at your neighbor's house or at your inlaws' house on passover?
Is it a good thing that you can't eat the meat at your neighbor's house all year?
Is it a good thing that when you go to a wedding or a bar mitzva you are not sure if you can eat the food because you don't know if the specific badatz keeps all the chumroth that you do?

I am not asking if the way we follow the halacha today is valid but is it ideal?

When it comes to nusach tefilla I actually don't think it is a problem at all. All the nushchaot are valid and it doens't make a difference if the person next to you davens a different nusach than you. But when it comes to Kashruth and other issues it does?

In the period of Sfirat Haomer the Rabanuth alleady faced a problem regarding weddings for different Edoth. For some ashkenazim it is ok to get married on Lag Baomer but not after that untill after shavuoth. For sfaradim it is actually not ok to get married on Lag Baomer but it is ok the day after lag baomer and after that. For Yemanites who follow the Rambam there is no problem at all during sfirat haomer.
The Rabanuth decides based on what Edah you are from. So it is one beith din deciding differently for different people.

Unfortunately there have been some non religous couples from different edoth who wanted to get married by the Rabanuth but got so fustrated that they decided to get a civil marriage in cyprus instead.
On this issue the Rabanuth actually recognized the problem and some have discussed the need to unify the minhag.