What? Of course there is, in the United States and many other countries. Protected classes are explicitly defined by the Civil Rights Act, Americans with Disabilities Act, and others. The bar owner can't refuse entry to a person because they are of a certain ethnicity, for example. But they absolutely can refuse entry to them for being a Nazi, or for any other attribute not protected in law.
Sure. What's your point? Your original comment seemed like you were trying to rebut my point that the Nazi (for literally any definition of Nazi you care to use) can just be removed from the bar. But it seems like you are not trying to rebut that, so I'm confused what this subthread is actually about.
> One could set up a dress code or any other arbitrary policy as a proxy to refuse entry to any group, without explicitly doing so.
Not in the US you can't. If a policy, even when applied equally, unduly affects a protected class, it's unconsitutional.
For example, if a restaurant enacts a "no headwear" policy it's still unconstitutional because by and large this is primarily going to affect the muslim population (and a segment of the jewish population), but will have very little effect on anyone else.
If the policy was instead "no headwear with words on it" the policy would NOT be unconstitutional because it does NOT unduly affect a specific group of people.
There are other exceptions, of course, generally around security. You can imagine a bank not allowing the full covering of ones face for security reasons even if that does appear to target people who wear burka's day to day.
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so long story short is that it's not super simple, but in the US you absolutely cannot try and get around it by proxy and there is established law on how to identify this.
https://en.wikipedia.org/wiki/Protected_group