Viewing child pornography online isn't a crime, the New York Court of Appeals ruled Tuesday in the case of a college professor whose work computer was found to have stored more than a hundred illegal images in its Web cache.

The court dismissed one of the two counts of promoting a sexual performance of a child and one of the dozens of counts of possession of child pornography on which James D. Kent was convicted. The court upheld the other counts against Kent, an assistant professor of public administration at Marist College in Poughkeepsie, N.Y.

Kent — who said at his sentencing that he "abhorred" child pornography and argued that someone else at Marist must have placed the images on his computer — was sentenced to one to three years in state prison in August 2009.

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The decision rests on whether accessing and viewing something on the Internet is the same as possessing it, and whether possessing it means you had to procure it. In essence, the court said no to the first question and yes to the second.

"Merely viewing Web images of child pornography does not, absent other proof, constitute either possession or procurement within the meaning of our Penal Law," Senior Judge Carmen Beauchamp Ciparick wrote for a majority of four of the six judges.

"Rather, some affirmative act is required (printing, saving, downloading, etc.) to show that defendant in fact exercised dominion and control over the images that were on his screen," Ciparick wrote. "To hold otherwise, would extend the reach of (state law) to conduct — viewing — that our Legislature has not deemed criminal."

Read the full appeals court ruling (.pdf)

In other words, "the purposeful viewing of child pornography on the internet is now legal in New York," Judge Victoria A. Graffeo wrote in one of two concurring opinions that agreed with the result but not with the majority's reasoning.

Kent's attorney, Nathan Z. Dershowitz, told msnbc.com that he hadn't yet had a chance to talk to his client, so he couldn't discuss what they would do next. But he agreed with Graffeo that the ruling means that "in New York, there is no crime" in simply viewing child pornography.

All of the judges agreed that child pornography is an abomination, but they disagreed whether it was necessary to "criminalize all use of child pornography to the maximum extent possible," as Ciparick wrote in the majority opinion. The majority said that was up to the Legislature, not the courts, to decide.

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The technical details revolve around copies of deleted files that remained in the cache of Kent's Web browser, which were the basis of the two counts that were dismissed. They were discovered, along with other materials, during a virus scan that Kent had requested because his computer was running slowly.

To demonstrate possession of the images in the cache, "the defendant's conduct must exceed mere viewing," Ciparick wrote, adding that "the mere existence of an image automatically stored in a cache" isn't enough.

Furthermore, the prosecution failed to prove that Kent even knew his Web browser had a cache in the first place, writing, "A defendant cannot knowingly acquire or possess that which he or she does not know exists."

Dershowitz said the "real problem here is that legislation is not keeping up with technology," arguing that federal courts also haven't fully addressed the legal standing of images stored only in a browser cache.

The federal statute outlawing possession of child pornography — 18 USC 2252A — doesn't mention browser caches. The few cases that have examined the issue at the federal level — notably a 2002 federal appeals case involving a Utah man and a 2006 federal appeals case involving a visitor to Las Vegas — generally conclude that cached images alone can establish possession if the defendant knows about the browser's caching function.

Both courts noted that it was hypothetically possible for the defendants to be innocent if they were ignorant of the cache function.

"Those statutes are probably not quite as incomprehensible, but they are anything but clear," Dershowitz said.

Kent's convictions on the other counts rested on other evidence, including a folder on his machine that stored about 13,000 saved images of girls whom investigators estimated to be 8 or 9 years old and four messages to an unidentified third party discussing a research project into the regulation of child pornography.

"I don't even think I can mail the disk to you, or anyone else, without committing a separate crime. So I'll probably just go ahead and wipe them," one of the messages said.

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