; or (ii) if a date is not specified in the notice of revocation, on the date on which the notice of revocation is published in the Federal Register. (8) Effect of revocation A revocation under paragraph (7) shall not affect any action or proceeding based on conduct that occurs before the effective date of the revocation. (9) Use of designation in removal proceedings The Attorney General shall not allow an alien in removal proceedings to raise, as a defense or an objection, a question relating to the validity of a designation under paragraph (1). (c) Modifications to a designation (1) In general With respect to a designation under subsection (b)(1), the Secretary may modify the designation if the Secretary determines that the criminal gang or cartel has— (A) changed name; (B) adopted a new alias; (C) dissolved and reestablished under 1 or more different names