Don't kill the messenger
Hold on to your hats folks:
31 USC § 5316. Reports on exporting and importing monetary instruments
(a) Except as provided in subsection (c) of this section, a person or an agent or bailee of the person shall file a report under subsection (b) of this section when the person, agent, or bailee knowingly—
(1) transports, is about to transport, or has transported, monetary instruments of more than $10,000 at one time— (A) from a place in the United States to or through a place outside the United States; or
(B) to a place in the United States from or through a place outside the United States; or
(2) receives monetary instruments of more than $10,000 at one time transported into the United States from or through a place outside the United States.
(b) A report under this section shall be filed at the time and place the Secretary of the Treasury prescribes. The report shall contain the following information to the extent the Secretary prescribes:
(1) the legal capacity in which the person filing the report is acting.
(2) the origin, destination, and route of the monetary instruments.
(3) when the monetary instruments are not legally and beneficially owned by the person transporting the instruments, or if the person transporting the instruments personally is not going to use them, the identity of the person that gave the instruments to the person transporting them, the identity of the person who is to receive them, or both.
(4) the amount and kind of monetary instruments transported.
(5) additional information.
31 USC § 5317. Search and forfeiture of monetary instruments
(b) Searches at Border.— For purposes of ensuring compliance with the requirements of section 5316, a customs officer may stop and search, at the border and without a search warrant, any vehicle, vessel, aircraft, or other conveyance, any envelope or other container, and any person entering or departing from the United States.
And for court cases involving the above:
US v. Hernandez-Salazar "Section 5317(b) is constitutional" Ninth Circuit.
US v. Ezeiruaku "The district court determined that there was no justification for applying the border
search exception to outgoing searches. We disagree, and for the reasons that follow, will reverse." Third Circuit.
US v. Stanley "Thus both incoming and outgoing border-crossing searches have several features in common: (1) the government is interested in protecting some interest of United States citizens, such as restriction of illicit international drug trade, (2) there is a likelihood of smuggling attempts at the border, (3) there is difficulty in detecting drug smuggling, (4) the individual is on notice that his privacy may be invaded when he crosses the border, and (5) he will be searched only because of his membership in a morally neutral class.
Although this may be an extension of present law, the similarity of purpose, rationale, and effect between the two types of border searches compels us to hold that the search here was proper." Ninth Circuit.