Not every splinter of sovereign citizen ideology believes the same things, but in general the movement is built on detailed interpretations of language written into laws and documents like the Constitution, court decisions and international treaties. Sovereign citizen logic usually draws a web of intricate connections between these various documents, and it bears a strong resemblance to the reasoning of conspiracy theorists. Sovereign citizens' claims that the U.S. is secretly controlled by foreign powers and that the government is "tricking" people into becoming citizens are, in fact, conspiracy theories.
But the justifications for sovereign citizens' beliefs are nebulous. One line of sovereign thought suggests that the United States is a corporation, not a country, and that all laws, including criminal laws, fall under the laws of the sea and international commerce, or admiralty law. By viewing all laws through the lens of commercial law (maritime and otherwise), sovereign citizens can frame every legal matter as a contract dispute. Since contracts can't be upheld if both parties didn't enter voluntarily, sovereign citizens claim they're not subject to laws as long as they rigorously maintain their refusal to enter into the contract. This helps explain why they sign their names unusually and refuse to acknowledge legal notices or bills.
Some sovereign citizens also find great significance in the fact that the U.S., along with virtually every other nation, took its currency off the gold standard in the 20th century. This means that currency the U.S. issues does not represent a real amount of gold for which it can be exchanged. Sovereign citizens interpret this to mean that the U.S. is in bankruptcy and used its citizens as collateral for foreign debt. So, according to them, the U.S. is no longer able to uphold, enter into or enforce contracts, and anyone aware of this supposed "secret" is no longer required to follow U.S. laws. Alternately, the lack of gold backing means U.S. money isn't "real" money, and therefore not taxable [source: Berger].
Then there's the matter of the 14th Amendment to the U.S. Constitution. Sovereign citizens argue that the first line — "All persons born or naturalized in the United States, and subject to the jurisdiction thereof, are citizens of the United States and of the State wherein they reside" — makes all U.S. citizens slaves to the government by overriding state laws with federal power. Therefore, they conclude, they can simply file paperwork with their county government renouncing the amendment, or that part of the amendment, and be free from the legal strictures that bind American "slaves" [source: Morton].
There are too many legal justifications for sovereign citizen claims to recount them comprehensively. Why are there so many? Because sovereign citizen ideology tends to assign invalid meaning to archaic laws or obscure texts. So, no matter what kind of trouble sovereign citizens get into, they can claim they are immune to it. But the legal system doesn't really recognize this philosophy.