A Missouri school district has been ordered to replace its web filter which blocks children from accessing pro-gay websites, but not anti-gay ones.

The New York Times says a judge ordered the change after a lawsuit claimed the filter used by the district was biased.

Schools are required to use internet filters to shield kids from obscene and pornographic content. It's unclear who developed this particular filter that blocked pro-gay content. The ACLU filed suit when the school district refused to change the filter to eliminate bias.

The lawsuit — believed to be the first of its kind — does not claim that this rural district of 4,200 students purchased the software with the intent of discriminating. Rather, it says, once there were complaints about the filter last year, school officials refused to replace it. An investigator for the A.C.L.U. has been able to figure out how the filter works, but not who developed it.

This is known: The creator goes by “Dr. Guardian” and lives in Fareham, England, in a house that, according to a Google Maps image, has children’s bicycles in the front yard.

“Some person, nameless and faceless, working out of his house in the United Kingdom, winds up determining what information students in Camdenton will have access to,” said David Hinkle, an expert on software filters with the A.C.L.U.

Camdenton officials say that any student who wants access to a pro-gay site that is blocked by the URLBlacklist filter can appeal to the district’s Web master. They point out that last May, when the A.C.L.U. sent a letter of complaint identifying four pro-gay sites that students did not have access to, the district unblocked them.

“We do not discriminate against gay people or anyone else,” Tim Hadfield, the superintendent, said in an interview.