Georgia [theregister.co.uk]- A US court has said the existence of child pornography images in the cache of a man’s computer did not mean that man had committed a crime under state law. The Court of Appeals in Georgia has reversed the man’s conviction.

A forensic computer analyst for the US Secret Service had testified in court that Edward Ray Barton’s laptop computer had been used to view 106 images of child pornography on the internet.

Barton was convicted on 106 counts of the sexual exploitation of children and jailed. Under appeal, though, three judges in the state of Georgia ruled that Barton did not break the law, which says that a person must have knowing possession of the images.

The images were stored on the hard drive of the computer, but only in the cache, a local store of files accessed on the internet designed to speed up browsing. Those images are not readily accessible without special software which he did not have, said the Secret Service expert.

The court said this could not count as a knowing possession of the files and that there was no evidence that Barton had consciously saved the files for later use.

Judge Yvette Miller said other cases had debated whether or not files had to be consciously saved in order for a crime to be committed.

“None of those decisions, however, found that a defendant may be convicted of possessing child pornography stored in his computer’s temporary internet file folders, also known as cache files, absent some evidence that the defendant was aware those files existed,” said Judge Miller in the court’s opinion.

She said in order to convict, the state had to show that a defendant took some action to save or download images, or that the defendant knew that the computer automatically saved files.

“There was no way that Barton could have learned of the cache files in the normal course of using his computer,” said Judge Miller. “Nor did the state present any circumstantial evidence that would have allowed the jury to infer Barton’s knowledge of these files, i.e. they did not show that Barton was an experienced or sophisticated computer user who would have been aware of this automatic storage process.”

The decision will not set a precedent across the US because it relates only to Georgia’s sexual exploitation laws, although many state laws on sexual exploitation carry similar requirements that a prosecution be based on knowing possession.

Last year a Pennsylvania court issued an opinion similar to that of Judge Miller. Judge Richard Klein said that a man who admitted viewing 370 images of child pornography had not broken the law because he had not sought to retain the images. Pennsylvania state law also criminalises “knowing possession” of images not the viewing of them.

“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,” Judge Klein said in his opinion. “The language used, 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 favour of the defendant.”

In January this year, however, the Superior Court of Pennsylvania withdrew Judge Klein’s opinion and said the case can receive a full court hearing. Judge Klein had argued it was wrong to convict the defendant in the case because a person had a right to advance notice that an act was illegal and criminal.

In the UK no such ambiguity exists. The Protection of Children Act makes it a crime to view images of child pornography irrespective of whether or not images are saved or stored.