12 U.S.C. § 1831d

In order to prevent discrimination against State-chartered insured depository institutions, including insured savings banks, or insured branches of foreign banks with respect to interest rates, if the applicable rate prescribed in this subsection exceeds the rate such State bank or insured branch of a foreign bank would be permitted to charge in the absence of this subsection, such State bank or such insured branch of a foreign bank may, notwithstanding any State constitution or statute which is hereby preempted for the purposes of this section, take, receive, reserve, and charge on any loan or discount made, or upon any note, bill of exchange, or other evidence of debt, interest at a rate of not more than 1 per centum in excess of the discount rate on ninety-day commercial paper in effect at the Federal Reserve bank in the Federal Reserve district where such State bank or such insured branch of a foreign bank is located or at the rate allowed by the laws of the State, territory, or district where the bank is located, whichever may be greater.

If the rate prescribed in subsection (a) exceeds the rate such State bank or such insured branch of a foreign bank would be permitted to charge in the absence of this section, and such State fixed rate is thereby preempted by the rate described in subsection (a), the taking, receiving, reserving, or charging a greater rate of interest than is allowed by subsection (a), when knowingly done, shall be deemed a forfeiture of the entire interest which the note, bill, or other evidence of debt carries with it, or which has been agreed to be paid thereon. If such greater rate of interest has been paid, the person who paid it may recover in a civil action commenced in a court of appropriate jurisdiction not later than two years after the date of such payment, an amount equal to twice the amount of the interest paid from such State bank or such insured branch of a foreign bank taking, receiving, reserving, or charging such interest.