United States?

It is a fantasy that white supremacists have.

An extremist who believes himself/herself to be immune from the law. 

There is in reality no such thing.  The answer from ? includes a link to a news story about nutcases who claim they are immune to the law due to being "sovereign citizens" but it is complete nonsense. 

One is a citizen of the United States in a few ways. Someone who is born in the US is automatically a citizen. So is someone born outside the US in a US territory to a parent that is a US citizen. Someone who is born outside the US to a parent that have spent a significant part of their life living in the US (what that is, I'm not sure). A foreign national can become a citizen of the US by applying for citizenship, going through the waiting period and going through the citizenship classes and eventually swearing allegiance to the United States.

probably a good citizen

It's really a contradiction in terms.  A citizen is a member of a sovereign country.  He can't be sovereign himself unless he's stateless, not a citizen.  The citizen and the state can't both be sovereign!

'Sovereign citizens' believe they are not members of the US, not subject to the US's laws or taxes or the responsibilities of citizenship.  But they still work, pay taxes, own property, follow laws, etc.  They still need a driver's license to drive and a fishing license to fish and a dog license to own a dog.

It reminds me of a riddle Will Rogers used to pose:

Q:  How many legs does a dog have if you call his tail a leg?

A:  Four.  Because callin' it a tail don't make it one!

I have heard a few of them try to explain it to the cops who pulled them over. So far I think it means you are listening to a narcissist with delusions of grandeur. Possibly schizophrenic, but high-functioning. I'm not a shrink, they leave that analysis to me. They seem to think law is a matter of self interpretation. So, cra-cra people. People who you want to avoid. 

‘Sovereign citizen’ convicted of biting off tip of Knoxville officer’s thumb

https://www.wate.com/news/local-news/sovereign-cit...