A contradiction exists in United States law. On the one hand, the IRS requires former citizens to follow an exit procedure and the State Department requires a $450 fee. On the other hand, earlier law establishes and protects expatriation as a fundamental right.
See also:
Freedom of Emmigration in East-West Trade, USC 19 § 2432 (expatriation is a fundamental right)
Is the taxation of US persons abroad constitutional?
The stalker: divorce from the United States is a messy process
Civil Disobedience, FBAR and Forms 8854 and 8938
The right of expatriation II: The Ninth Amendment
The right of expatriation