Charges have been dropped against a US teacher accused of looking at porn whilst in charge of a classroom of kids.

In what has been a bizarre and controversial case, one Julie Amero was indicted on charges of endangering the morals of a minor, way back in 2004.

In October of that year, Amero was substituting at a middle school in Norwich, Connecticut.

She claims that she was simply surfing the web looking at sites about hairstyles, but then her screen was filled with pop-up porn pages - something her seventh-grade students were quick to notice.

Amero says she had no idea how to stop it, and as she had been warned before against shutting down machines, she rushed to the teacher's staff room for help. But instead of some friendly IT advice, she ended up in court.

And what a case - on one side - police officer Mark Lounsbury, who says Ars Technica: "examined the school computer - convinced a jury that Amero had been surfing porn sites, recklessly exposing kids to a lesson in lewdness" and on the other - the head of a Florida-based computer security expert who got involved after writing about the case in his blog.

The man in question - Alex Eckelberry - ended up finding a forensic witness who'd testified on Amero's behalf before putting together an entire forensic team to help the hapless teacher.

Interestingly, they found that the school computer's antivirus software was months out of date at the time of the incident and the school's content filter subscription had also lapsed - despite the testimony of the school's IT manager.

And they also found that a piece of spyware called newdotnet had been installed on the Windows 98 machine.

The police officer was also revealed to have misled the jury by making leading statements.

Amero's conviction has now been overturned with a new trial being planned but the teacher has now become sick with the stress of the whole thing.

So instead the charges have been dropped and Amero fined $100 as well as having her professional credentials revoked.

That's hardly justice for someone who did nothing wrong.