12 U.S.C. § 56: Prohibition on withdrawal of capital; unearned dividends

No association, or any member thereof, shall, during the time it shall continue its banking operations, withdraw, or permit to be withdrawn, either in the form of dividends or otherwise, any portion of its capital. If losses have at any time been sustained by any such association, equal to or exceeding its undivided profits then on hand, no dividend shall be made; and no dividend shall ever be made by any association, while it continues its banking operations, to an amount greater than its undivided profits, subject to other applicable provisions of law. But nothing in this section shall prevent the reduction of the capital stock of the association under section 59 of this title.