Bianco described Miller as a “sovereign citizen,” referring to a loose collective of extreme libertarians who believe that the government cannot legally exercise authority over them.

Authority= the moral right to govern over someone else's life. The right to be a slave master or his/her enforcement to rule over another.

Sovereign= An individual born free. Self ownership of him/herself. And not a slave or servant to any one or any party of force that calls themselves government.

Citizen= a servant of the state. Has no rights because they are a slave to will of the state.

Sovereign-citizen= An oxymoronic term where each word has exactly the opposite meaning.

Bianco= A puppet, a sycophant imbecile. A citizen. Serving his master's agendas.

"Legal to exercise authority"= An idiotic phrase to give excuse to use force against a free people to rule over their lives.

"referring to a loose collective of extreme libertarians"= despite popular opinion, because popular opinion is controlled anyways, a sovereign individual is not a libertarian nor radically dangerous. They don't believe in pertaining to any government parties. They are not republican or democrats. Not communist, or authoritarian of any sort. They are simply free individuals who don't believe in the cult of statism.

Feel free to add more to that.