There is a good reason for separation of church and state, this case being just one example.
All religiouns have a body of laws, which is why each law, Jewish, Christian, Sharia should be subject to
equal standards under the Constitution.
For example, some town in Texas passed a law banning Sharía courts. This should be unconstitutional because it is denomination specific, and ignores exactly the same courts operated by the Catholics, Episcopals, Methodists, and Jews, e.g. no different from the secular laws regarding arbitration.
Example if my neighbor has parties that keep me awake at night, not against civil law. I complain to him, and he agrees that he and I select a third party to settle the issue and to abide by his decision, which is say to post a sound meter in the street, and to pay so much per decible above the agreed limit during specified hours. That is a legitimate contract, and the civil courts would hold him accountable for the damages. In America there are all sorts of unofficial courts, that can result in binding decisions. The fact is that arbitration saves the tax payers a lot of money, and is cheaper on the litigants. One example of this I have experienced in Califonra, School districts have a personnel commission. If an employee and the school board agree, this commission hears the case and makes a judgement binding on both the employee and the board (as an unofficial friend of the court, I have written the case for three non teacher employees, who have won over the board in each case. In one case, the commission granted far more then the fired woman was asking, because of the evidence that came out in the hearing. Here is how it happened.
There is a state law that says if the home language of a certain percentage of the students in a given school is not English, accomodation for that language should be provided for. In this case, Spanish met the criteria, and the district has always cheated in meeting it. In this woman´s case, grandmother, college graduate, bilingual spanish-English, she was hired as a secretary to a racist counselor. Under the union contrac, if Spanish was a job requirement, she should recieve a pay increment over that of monolingual employees at the same pay grade.
Here immitiate boss was unhappy having to deal with Spanish speaking, mostly mothers in disciplinary matters, and found fault with this secretary in two areas: 1. she took to much time and did not translate him exactly (see below) she also fussed to much making the mothers, usually who came with younger kids, making them comfortable. 2. She was often not available to him because she was always somewhere else when he needed her (e.g. translating for the principal, deans, attendance, and other counselors, as she was the only one who could do the job. In what was going to be her last year before retirement, the following June (an important year because her pension would be higher if she was 65 and had held the job for 10 years, so he had the principal fire here before Christmas. My case for her was based on several factors, that for 10 years she had been exploited by not being paid the legal increment. The counselor was insensitive to the needs of the Spanish speaking parents in that when a mother comes in with young kids, the session runs smoother if the mother is comfortable and not distracted by the kids, and the so called mistraslation, was simply because the terms used in "ed speak" do not translate well into a second language (Example, we use the word "cume" short for cumulative folder which each student has that contain all his records, so when he said "cume file", she translated it as "archive folder containing the student´s records". This is just one example, rather obvious considering that this guy was a non Spanish speaking, hispanic hired under affirmatie action, he would recognize that she was not translating exactly, but unaware of what she was saying - in fact doing him a favor. The case was filed in January, but not heared until the next December. She won, what she had asked for pay and retirement credit from December to June of her 10th year, and was reinstated, which meant she was in her 11th year, so her retirement was based on 11 years of service since she was illegally discharged. Not only that she got 11 years of her unpaid Spanish speaking increment, plus interest.
The board, could have chosen to force her to go to court, but their lawyer after reading my case for her, knew that they would not only lose, but have to pay for her lawyer (as opposed to a cost free union arbitrator), plus their wn legal team, and the possibility of punitive damages.
Where church courts are usually upheld are in cases of divorces, and disputes between members, because these are a bettter solution then civil court procedings.