CA Court of Appeals provides guidelines for “knowing posession”.
In People v. Michael James Tecklenburg, (2009, 169 Cal. App. 4th 1402) the California Court of Appeals considered the relevance and applicability of involuntary "pop-ups" and temporary Internet files (TIF or "cache") to the applicable statute. California’s Penal Code section 311.11(a) makes it illegal to "knowingly posses or control" depictions defined as child pornography according to state law (P.C. 314, subd. d). The court specifically considered the variables required to establish "control".
In Tecklenburg, the court denied appeal based on the State’s discovery having established the cumulative applicability of the following variables:
- the user actively searched for child porn;
- the user visited child porn web sites;
- the user explored beyond the first page of said web sites;
- the user clicked on images on, at least, one web site;
- the images appeared and were accessed multiple times;
- the user enlarged thumbnail images;
- the images were “part of a series or collection”;
- the size and format did not match that of a pop-up;
- similar, and sometimes identical, images were found on both the user’s home and work computers.
While I don’t agree with the entirety of the court’s findings, said computer forensics expert Jeff Fischbach, nor am I comfortable that the court fully appreciates the non-standardized and ever-evolving nature of the Web, or the limitations of computer forensics, I do think that the decision itself serves as a good minimum benchmark, or litmus test, for both prosecution and defense in similar cases.