Credit cards (and the interest they charge) are not regulated by the federal government but rather by the state in which they are headquartered. For this reason most credit card issuers are set up in such states as South Dakota, Utah or Delaware, states with very weak or nonexistent usury laws.

Under the recent Credit CARD Act that took effect in February 2010, rates cannot increase on existing balances if your account is in good standing. If you are hit with an increase, you may cancel your card and pay off the balance at the old rate.