8 U.S. Code § 1156 - Unused immigrant visas
If an immigrant having an immigrant visa is denied admission to the United States and removed, or does not apply for admission before the expiration of the validity of his visa, or if an alien having an immigrant visa issued to him as a preference immigrant is found not to be a preference immigrant, an immigrant visa or a preference immigrant visa, as the case may be, may be issued in lieu thereof to another qualified alien.
1996—Pub. L. 104–208 substituted “denied admission to the United States and removed” for “excluded from admission to the United States and deported”.
1965—Pub. L. 89–236 substituted provisions allowing immigrant visas or preference immigrant visas to be issued to another qualified alien in lieu of immigrants excluded or deported, immigrants failing to apply for admission, or immigrants found not to be preference immigrants, for provisions relating to revocation of approval of petitions which, with minor amendments, were transferred to section 1155 of this title.
Amendment by Pub. L. 104–208 effective, with certain transitional provisions, on the first day of the first month beginning more than 180 days after Sept. 30, 1996, see section 309 of Pub. L. 104–208, set out as a note under section 1101 of this title.