“Any person who in the special maritime and territorial jurisdiction of the United States, or on any land or building owned by, leased to, or otherwise used by or under the control of the Government of the United States, or in the Indian country as defined in section 1151 of this title, knowingly possesses […] 1 or more books, magazines, periodicals, films, video tapes, or other matter which contain any visual depiction shall be fined under this title or imprisoned not more than 10 years,”
The only affirmative defense in informing the police and immediate destruction.
18 U.S. Code § 2252