19 CFR § 134.51 - Procedure when importation found not legally marked.
(a) Notice to mark or redeliver. When articles or containers are found upon examination not to be legally marked, the Center director shall notify the importer on Customs Form 4647, or its electronic equivalent, to arrange with the Center director's office to properly mark the article or containers, or to return all released articles to Customs custody for marking, exportation, or destruction.
(b) Identification of articles. When an imported article which is not legally marked is to be exported, destroyed, or marked under Customs supervision, the identity of the imported article shall be established to the satisfaction of the Center director.
(c) Supervision. Verification of marking, exportation, or destruction of articles found not to be legally marked shall be at the expense of the importer and shall be performed under Customs supervision unless the Center director accepts a certificate of marking as provided for in § 134.52 in lieu of marking under Customs supervision.