This short post is actually a comment I placed on The Honest Hack.
I happened to be living in France the time the government banned the Islamic headscarf. I thought it was wrong. And I think the ban on the Turban for the Gardaí is wrong.
Of course the fluffy notion that we should all respect one another, and let everyone practice their culture no matter what is sheer madness. Like all ideas that claim to be universal it will be a disaster. There has to be a meeting half way - both assimilationism (a la France, where minorities are simply not recognised, everyone being seen only as a citizen of the republic) and laissez-faire multiculturalism (as in Britain where the idea was that everyone can have their own community with, if need be its own culture, language, and religion) are doomed to fail.
If we meet half way, we have to draw lines. We would not and should not allow female mutilation just because it's part of African culture. We could not allow, say, Muslims females to demand that all-female public facilities be provided in place of those which society has decided should be mixed.
So yes there are limits. No absolutes. This means the extra effort and complexity of making calls on a case by case basis. And building one compromise on another. That's basically the way most of our other social norms have evolved.
If we need to make a call on the turban, let's start by asking, what benefit is there to society in banning the turban in the Gardaí? Precious little I imagine. What are the gains? A visible gesture towards integration. As matters go, this is an easy call. A shame if we miss it.