According the world's most accurate encyclopedia . . . "The sovereign citizen movement is a loose grouping of American and Commonwealth litigants, commentators, tax protesters, and financial-scheme promoters. Self-described "sovereign citizens" see themselves as answerable only to their particular interpretation of the common law and as not subject to any government statutes or proceedings."
Basically, it's an effective shortcut to getting a BEATDOWN from local police . . . Example:
Police, courts wrestle with sovereign citizen movement