Police blotter: Child porn in Web cache OK

"Police blotter" is a weekly News.com report on the intersection of technology and the law.

What: Pennsylvania man appealed his conviction for knowingly possessing downloaded child pornography, saying he didn't know it was in his Web browser's cache.

When: The Pennsylvania Superior Court ruled on November 2.

Outcome: Court threw out conviction, saying state law criminalized only knowingly possessing child pornography, not simply viewing it.

What happened, according to court documents:
Anthony Diodoro was convicted of 30 counts of child pornography possession and one count of criminal use of a communication facility. He was sentenced to 9 months to 23 months in prison.

His conviction arose out of a slightly unusual situation: Prosecutors successfully proved that Diodoro had viewed child pornography sites and pointed to his Web browser's cache as evidence. (A browser cache is a temporary storage location for Web pages, so that if the same page is visited again, it can be quickly reloaded from the hard drive.)

But prosecutors did not prove that Diodoro actually knew the illegal images were saved to the cache, a common situation for novice users.

That's crucial, because section 6312(d) of Pennsylvania's criminal code says: "Any person who knowingly possesses or controls any book, magazine, pamphlet, slide, photograph, film, videotape, computer depiction or other material depicting a child under the age of 18 years engaging in a prohibited sexual act or in the simulation of such acts commits an offense."

The judges agreed that Diodoro viewed child pornography (some 370 images worth, in fact) but ruled that the wording of the law only criminalized knowingly possessing it. They reversed his conviction.

This is different from other cases that have appeared on Police Blotter in the past. In July, the 9th Circuit upheld a defendant's child porn conviction, in part because the evidence showed he looked at the cached images. In a case involving a Naval officer, he allegedly had saved images in addition to cached images.

In another case, called U.S. v. Tucker, the 10th Circuit upheld a defendant's conviction because he cleared his Web browser's cache to avoid being caught with saved child porn. The logic: Because he knew about the existence of the cache, he had knowingly possessed the images at least temporarily.

This is another odd result of laws written during a time when contraband existed only in physical form. It implies, for instance, that it would be perfectly legal to watch (though not distribute) child porn videos streamed through a site like YouTube, and that it would be legal to browse child porn Web pages if a browser's cache was disabled.

Excerpts from the Pennsylvania court's opinion (click here for PDF):
This is an issue of first impression in Pennsylvania. We have found no case exactly on point in which a conviction for "possession" of child pornography for simply viewing it on a Web site without any evidence that the defendant knew the image was being saved on the computer's hard drive. In cases from other jurisdictions affirming such convictions, there was evidence that the defendant knew the images were being stored, and usually distinguished those cases from the situation where the defendant merely viewed the images without knowing they were being stored. Those cases point out that to establish possession, a defendant must know that the image is being stored, so he or she knows he or she has the ability to save, print, or e-mail the images to others.

We note that it is well within the power of the legislature to criminalize the act of viewing child pornography on a Web site without saving the image. The language used in section 6712(d), however, is simply "possession." Because this is a penal statute with an ambiguous term when it comes to computer technology, it must be construed strictly and in favor of the defendant. A defendant must have fair notice that his conduct is criminal. Because of the ambiguity, sufficient notice was not provided here. For this reason, we are constrained to reverse and leave it to the legislature to clarify the language if it intends to make the mere "viewing" of child pornography a crime.

At trial, the commonwealth's computer forensics expert testified that when a Web site is viewed, the image is automatically saved to an Internet cache file. The purpose is to save time, so that if the site is viewed again, the old file can be quickly uploaded rather than requiring the time to reload the file...

We hold that absent specific statutory language prohibiting the mere viewing of pornographic images or evidence that the defendant knowingly downloaded or saved pornographic images to his hard drive or knew that the Web browser cached the images, he cannot be not criminally liable for viewing images on his computer screen. Therefore, we conclude that the evidence was insufficient to sustain Diodoro's conviction for knowing possession of child pornography under section 6312(d).