22 U.S. Code § 8804 - Imposition of sanctions with respect to the sale, supply, or transfer of certain materials to or from Iran
The requirement to impose sanctions under paragraph (1) shall not include the authority to impose sanctions relating to the importation of goods under paragraph (8)(A) or (12) of section 6(a) of the Iran Sanctions Act of 1996, and any sanction relating to the importation of goods shall not count for purposes of the requirement to impose sanctions under paragraph (1).
The President shall prohibit the opening, and prohibit or impose strict conditions on the maintaining, in the United States of a correspondent account or a payable-through account by a foreign financial institution that the President determines knowingly, on or after the date that is 180 days after January 2, 2013, conducts or facilitates a significant financial transaction for the sale, supply, or transfer to or from Iran of materials the sale, supply, or transfer of which would subject a person to sanctions under subsection (a).
Materials described in this subsection are graphite, raw or semi-finished metals such as aluminum and steel, coal, and software for integrating industrial processes.
The President may not impose sanctions under subsection (a) or (c) with respect to a person if the President determines that the person has exercised due diligence in establishing and enforcing official policies, procedures, and controls to ensure that the person does not sell, supply, or transfer to or from Iran materials the sale, supply, or transfer of which would subject a person to sanctions under subsection (a) or conduct or facilitate a financial transaction for such a sale, supply, or transfer.
For purposes of this section, the term “national balance sheet of Iran” refers to the ratio of the assets of the Government of Iran to the liabilities of that Government.