United States v. Alden Dickerman, 954 F.3d 1060

Dickerman was investigated for accessing child pornography on Freenet, a decentralized P2P network that breaks files into encrypted "blocks" distributed across nodes.
Law enforcement (Becker) used modified Freenet nodes and Dr. Brian Levine’s statistical algorithm to distinguish "original requesters" (who know the file requested) from passive "relayers." Data showed Dickerman’s IP requested 69 blocks of a suspected child-pornography file.
Detective Slaughter prepared an affidavit summarizing Freenet, officers’ qualifications, Becker’s undercover collection of keys, and that the number/timing of requests indicated Dickerman was the apparent original requester; the affidavit did not detail Levine’s algorithm or its error rate.
A state judge signed the warrant; officers seized Dickerman’s computer and discovered child pornography. Dickerman was charged, moved to suppress, and the magistrate and district court denied suppression, citing Leon’s good-faith exception.
On appeal Dickerman argued (1) the affidavit lacked sufficient indicia of probable cause to show he was an original requester and (2) the issuing judge acted as a "rubber stamp." The Eighth Circuit affirmed, applying Leon.

Issue	Plaintiff's Argument	Defendant's Argument	Held
Whether the affidavit was so lacking in indicia of probable cause that officers’ reliance was unreasonable	Affidavit failed to explain how officers distinguished requester vs. relayer (no algorithm details or error rate), so it lacked probable cause	Affidavit contained detailed facts about Freenet, officers’ expertise, Becker’s investigation, and officers knew additional technical validations not in affidavit	Affidavit was not so deficient; officers’ reliance on the warrant was objectively reasonable under Leon
Whether the issuing judge abandoned neutral role ("rubber stamp") by signing without understanding affidavit	Judge later testified he did not understand technical details and asked no questions, showing he did not perform a detached review	Judge read the affidavit, had prior experience with similar warrants, Missouri law barred oral testimony, and officers had no reason to believe judge was biased or passive	Judge did not abandon role; silence/technical unfamiliarity did not make him a rubber stamp; Leon good-faith exception applies

United States v. Leon, 468 U.S. 897 (establishing the good-faith exception to the exclusionary rule)
United States v. Clay, 646 F.3d 1124 (8th Cir. 2011) (standard of review and that Leon may be considered before probable cause)
United States v. Farlee, 757 F.3d 810 (8th Cir. 2014) (may consider information outside affidavit when evaluating objective reasonableness)
United States v. Perry, 531 F.3d 662 (8th Cir. 2008) (enumerating Leon exceptions)
United States v. Decker, 956 F.2d 773 (8th Cir. 1992) (judge failed to read warrant—example of abandonment)
United States v. Hallam, 407 F.3d 942 (8th Cir. 2006) (magistrate silence does not automatically equal rubber-stamp)
United States v. Scroggins, 361 F.3d 1075 (8th Cir. 2004) (focus on officer reasonableness in good-faith inquiry)
Connally v. Georgia, 429 U.S. 245 (1977) (judge pecuniary interest undermines neutrality)
Lo-Ji Sales, Inc. v. New York, 442 U.S. 319 (1979) (judge participation in investigation undermines neutrality)