The Prince William County school system has removed a filter from school computers that prevented students from accessing information about lesbian, gay, bisexual and transgender issues.

Software on school computers screens out sexually explicit Web sites in compliance with state and federal law. But the software, created by Blue Coat Systems, also included a filter that blocks content from organizations such as the Gay, Lesbian and Straight Education Network and the It Gets Better Project, an anti-bullying initiative.

The American Civil Liberties Union of Virginia sent a letter to Superintendent Steven L. Walts in April asking for the “LGBT filter” to be removed. The school system responded Wednesday by removing that filter from its computers while keeping the rest of the security software in place.

“Internet filtering is difficult, sometimes imprecise, and constantly evolving. It is nearly impossible to find the perfect balance between the protection of students, freedom of speech and equal access,” said Keith Imon, the school system’s associate superintendent for communications and technology services. “However, the decision to discontinue the use of the LGBT filter is within this balance.”

Officials said that inappropriate content will still be caught by an “automatic filtering process.” The district is also working with Blue Coat to identify sites that might need to be filtered through other categories now that the LGBT filter is no longer being used.

“We’re happy that Prince William has chosen not to discriminate against Web content that might be useful to lesbian and gay youth,” said Rebecca Glenberg, legal director of the ACLU of Virginia. She said she was unaware of any other Northern Virginia school systems that use the LGBT filter.

The ACLU has contacted school systems across the country about Web filtering in a national “Don’t Filter Me” campaign. In 2009, two Tennessee systems removed an LGBT filter after being sued by the ACLU. Schools in Maryland, New Jersey and Texas removed such filters after being contacted by the organization.