What document is mainly required for acquiring evidentiary materials in a customs investigation?

In the context of a customs investigation, the most relevant document for acquiring evidentiary materials is a search warrant. A search warrant is issued by a judge and grants law enforcement personnel the authority to search a specific location for evidence related to a suspected crime, such as customs violations. The warrant is based on probable cause and outlines the areas to be searched and the items to be seized.

A grand jury subpoena is primarily used in the context of criminal investigations to compel testimony or the production of documents; however, it does not allow for the physical search of a residence or business, which is often necessary in customs investigations. A customs declaration typically involves reporting goods and currency to customs authorities but does not serve as a means to gather evidence during an investigation. An affidavit of compliance may be utilized in certain administrative processes but is not the principal document for acquiring evidence in the context of a search.

Thus, the use of a search warrant is critical in securing the evidence directly relevant to customs-related inquiries and ensures that the search is conducted legally and within the boundaries of the law.