The American Civil Liberties Union and the ACLU of Pennsylvania have sent a letter to the Governor Mifflin School District in Shillington, PA which threatens legal action if the district doesn’t address the claims of high school student Maison Fioravante. While performing research on Governor Mifflin High School computers, Fioravante discovered that many educational LGBT sites were being blocked by the school’s content filter.

When she tried to access certain LGBT sites for research purposes, Fioravante was met with a filter notice that cited a “sexuality” filter as the reason for the blocking. She posted a YouTube video detailing her situation and also began a petition on change.org asking the high school to stop blocking LGBT sites. The petition has amassed over 3,300 signatures and drew the attention of the ACLU.

In their letter, the ACLU notes that this sort of filtering is considered viewpoint discrimination that was recently ruled unconstitutional in a recent court case.

They state that the “sexuality” filter seems to be only blocking LGBT-oriented sites.

But it’s not just LGBT sites that the school district’s filter (running Smoothwall software) is blocking. Apparently, the firewall is preventing access to anti-gay websites from organizations like the National Organization for Marriage and the the Family Research Council. The reason given is that these sites are blocked due to “intolerance.”

The ACLU says that this is also ill-advised, as blocking even an “intolerant” viewpoint is an independent violation of the First Amendment.

The ACLU gives the school district until March 14th to address their concerns before they proceed with legal action.

“The ACLU respectfully requests that Governor Mifflin School District immediately reconfigure its Smoothwall filtering system so that it operates in a viewpoint-neutral manner or the District should find an alternate software vendor with a product that satisfies the requirements of both the Children’s Internet Protection Act (“CIPA”) and the First Amendment. Please contact us by Thursday, March 14, to advise us whether you will make the requested changes to the filter and if so, how you intend to do so,” says the letter.

[h/t The Verge]