A federal judge has ruled that the government's use of metadata as evidence against an alleged child pornographer didn't violate his privacy rights.

Donald Post, 69, was already a registered sex offender when the FBI arrested him in August. Their investigation against him started with online photos of a man, face unseen, molesting a four-year-old girl. They showed no other identifying details, however, and the uploader had used TOR, an anonymizing browser, to mask his Internet protocol address.

But the photographer hadn't turned off his iPhone default settings, which automatically include embed GPS metadata in a photo. The FBI ran those coordinates and found they were near Post's home in League City, Texas, and Post admitted to taking the photos.

Metadata, roughly defined as information about communication or media rather than their contents, has been a particularly touchy subject since former National Security Agency contractor Edward Snowden leaked agency documents in June. His first leak, for instance, showed that the NSA had been tracking phone metadata—lengths of calls, who called who, and when—of practically everyone in America.

Courts have been since been conflicted on bulk metadata collection's legality, further complicated by the fact that the Foreign Intelligence Surveillance Court that authorized the NSA only justified that practice on Aug 29.

But in his Jan. 30 ruling on Post, Judge Gregg Costa said the two types of metadata were apples and oranges, since the photo's uploader had made the information publicly available, even if he did so unknowingly:

Whatever the ultimate outcome of that issue in higher courts, whether an individual lacks a privacy interest in dialed numbers because those numbers are necessarily disclosed to his phone company is a much different question than whether an individual loses his privacy interest in an item because he voluntarily makes it publicly available on the internet.

Post faces up to 50 years in prison for producing the image alone, plus an additional 10 for being a previous sex offender.

Photo by hello turkey toe/Flickr | Remix by Fernando Alfonso III