42 U.S.C. § 2000aa: Searches and seizures by government officers and employees in connection with investigation or prosecution of criminal offenses

there is probable cause to believe that the person possessing such materials has committed or is committing the criminal offense to which the materials relate: Provided, however , That a government officer or employee may not search for or seize such materials under the provisions of this paragraph if the offense to which the materials relate consists of the receipt, possession, communication, or withholding of such materials or the information contained therein (but such a search or seizure may be conducted under the provisions of this paragraph if the offense consists of the receipt, possession, or communication of information relating to the national defense, classified information, or restricted data under the provisions of section 793, 794, 797, or 798 of title 18, or section 2274, 2275, or 2277 of this title, or section 783 of title 50 , or if the offense involves the production, possession, receipt, mailing, sale, distribution, shipment, or transportation of child pornography, the sexual exploitation of children, or the sale or purchase of children under section 2251, 2251A, 2252, or 2252A of title 18); or there is reason to believe that the immediate seizure of such materials is necessary to prevent the death of, or serious bodily injury to, a human being. there is probable cause to believe that the person possessing such materials has committed or is committing the criminal offense to which the materials relate: Provided, however , That a government officer or employee may not search for or seize such materials under the provisions of this paragraph if the offense to which the materials relate consists of the receipt, possession, communication, or withholding of such materials or the information contained therein (but such a search or seizure may be conducted under the provisions of this paragraph if the offense consists of the receipt, possession, or communication of information relating to the national defense, classified information, or restricted data under the provisions of section 793, 794, 797, or 798 of title 18, or section 2274, 2275, or 2277 of this title, or section 783 of title 50 , or if the offense involves the production, possession, receipt, mailing, sale, distribution, shipment, or transportation of child pornography, the sexual exploitation of children, or the sale or purchase of children under section 2251, 2251A, 2252, or 2252A of title 18); there is reason to believe that the immediate seizure of such materials is necessary to prevent the death of, or serious bodily injury to, a human being; there is reason to believe that the giving of notice pursuant to a subpena duces tecum would result in the destruction, alteration, or concealment of such materials; or all appellate remedies have been exhausted; or there is reason to believe that the delay in an investigation or trial occasioned by further proceedings relating to the subpena would threaten the interests of justice. In the event a search warrant is sought pursuant to paragraph (4)(B) of subsection (b), the person possessing the materials shall be afforded adequate opportunity to submit an affidavit setting forth the basis for any contention that the materials sought are not subject to seizure.