No religious or cultural group should be allowed to have their own legal system or exclusively police themselves. There must be one set of laws for all citizens and legal residents, and here in the US, that must be the civil laws enshrined or backed by the Constitution.
I don't think anyone cares if those of similar backgrounds choose to live near each other and associate mostly with those they identify with. But no group, religious, cultural, or otherwise, should be allowed to establish exclusive enclaves where their own set of rules applies and where the civil authorities, including the police, fear to tread.
I have heard of such areas in London and Paris where Islam and Sharia Law reign supreme, though their existence is officially denied. I know for a fact that there are areas in and around New York City where certain sects of Jews run their own neighborhoods and the police simply let them. Even reports of child abuse by certain of their leaders are covered up and the people are warned not to talk about such things to outsiders.
A recent reality TV show revealed that certain Romanian gypsy bands forbid education to their daughters and marry them off to each other as young as possible. Certain outlying Mormon groups openly practice polygamy and the local governments turn blind eye while they intentionally become a drag on society by having as many children as possible and expecting the welfare agencies to support them.
The US Constitution forbids any laws respecting the establishment of any religion. I hold that giving any religion special privileges like running their own show in their own communities and policing themselves IS the de facto establishment of that religion. So is giving religious organizations special tax treatment, but that's another topic.
The US government need to make it abundantly clear that while people are free to congregate and live near and among whomever they want, there is one set of laws that applies to everybody. No one can be allowed to impose their religious or cultural laws, superstitions, practices, or taboos on anyone else. Saying something is required or justified by one's religious belief is no get-out-of-jail free card. If it's a crime, it's a crime. End of story.
This position needs to be even more stringently enforced when we're talking about someone who wants to enter this country, whether to live or even just to visit. Each one must be individually screened and vetted to determine if they truly want to embrace American culture and the freedom of the individual and live under our laws. They must not be allowed to enter if they want to bring their misogynous, hateful, bigoted religious or cultural beliefs and superstitions with them and impose them on others, including family members. They must prove that they totally reject jihad and any other form of terrorism or coercion to force others to believe as they do. If they don't want to live under the freedom that our laws guarantee them, and extend that same freedom to others, including females and other individuals typically oppressed by organized religion and tribal cultures, then they must not be allowed to enter and spread their filthy bile here.
We are supposed to all live under the temporal civil laws backed by the Constitution, not laws based on religious superstition and tradition. I hope that never changes.