How have courts treated cached files, thumbnails, and deleted CSAM artifacts in possession prosecutions?

1. How courts distinguish “possession” from forensic remnants

Courts treat possession as a compound question of knowledge plus dominion and control, not merely a storage-location inquiry; thus artifacts created automatically by systems—browser caches, thumbnails, and orphaned deleted files—are often considered insufficient standing alone to prove knowing possession ^{[1] [2]}. The Ninth Circuit in Kuchinski refused to equate automatic browser caching with knowledge unless the government showed the defendant was aware of and could access the cached files, warning that otherwise conviction would “turn abysmal ignorance into knowledge” ^{[1] [2]}.

2. Deleted files and unallocated space: a recurring appellate concern

When images appear only in unallocated or slack space, courts have pushed back against converting raw forensic recovery into proof of mens rea; United States v. Flyer is a touchstone where the Ninth Circuit reversed because materials in unallocated space were inaccessible without specialized tools and thus did not demonstrate usable possession ^[1]. Lower and appellate courts have similarly vacated convictions when the State could not show that the defendant knew the files existed or had the practical ability to locate and view them ^{[2] [3]}.

3. Thumbnails and caches: context matters, activity evidence matters more

Some opinions permit conviction where thumbnails or cached copies combine with other indicators of user activity—search history, access logs, or browsing behavior—that tie a person to deliberate viewing or retention; courts thus treat thumbnails and temporary internet files as probative only when accompanied by corroborative evidence establishing awareness and control ^{[1] [4]}. Legal scholarship and defense practitioners emphasize this threshold: temporary internet files can be innocent byproducts of web architecture unless prosecutors show the user intentionally sought or retained the content ^{[2] [5]}.

4. Attribution and who used the device: the deciding battleground

Beyond artifact analysis, attribution is often decisive; courts and commentators note that a device or IP address is not proof of an individual’s conduct, and many rulings demand additional artifacts—user accounts, logs, or direct evidence of user interaction—to connect files to a specific person’s dominion and control ^{[1] [6]}. The practical upshot is that forensic remnants frequently generate leads but do not replace the prosecutor’s burden to prove who accessed, viewed, or intentionally stored the material ^{[1] [6]}.

5. Divergent lines and policy tensions

Although several circuits apply the stricter knowledge-and-control standard, the case law is not uniform and scholarship documents split approaches: some courts have been more willing to treat certain automatic copies as constructive possession while others protect defendants from liability for artifacts that arise without affirmative action ^{[5] [4]}. This divergence fuels policy debates about how to balance child-protection imperatives with protecting defendants from convictions based on opaque system behavior and forensic reconstruction ^{[7] [4]}.

6. Where the law is heading and evidentiary best practices

Practitioners and commentators advise prosecutors to pair recovered artifacts with behavioral or account-level evidence—searches, user profiles, timestamps consistent with viewing, or admissions—to meet the legal standard; defenses continue to focus on technical explanations for caches, thumbnails, and deleted remnants and on the government’s obligation to prove knowledge and control ^{[1] [6] [2]}. Recent discussions about AI-generated imagery and statutory gaps add complexity but do not alter the core evidentiary rule courts apply today: forensic remnants alone rarely establish knowing possession without additional proof tying the material to an accountable actor ^{[8] [9]}.