Internet Filtering: Don't Do It

To filter or not to filter: that's a big decision public libraries face. Ever since the Supreme Court upheld the Children's Internet Protection Act (CIPA), libraries have felt pressure to filter Internet on public access computers.

If you read the spoiler alert headline of this blog post, you'll see that I'm completely against filtering the Internet on public access computers. I didn't always feel this strongly; in fact, I wasn't really informed enough to have an opinion one way or another. After hearing a presentation on the impact of CIPA and filtering, however, my mind is completely made up: Internet filters do more harm than good.

At PLA 2014, Sarah Houghton of the San Rafael Public Library and Deborah Caldwell-Stone, deputy director of the ALA Office for Intellectual Freedom, discussed the history of CIPA and the effectiveness of filters. Both agree: filtering creates barriers to digital inclusion, freedom of information, and education. Houghton has written extensively about how why Internet filters don't work and why librarians shouldn't filter in her blog Librarian in Black. Caldwell-Stone has also written about the history of CIPA and filtering and the First Amendment for American Libraries.

CIPA and Filters: A Quick History

CIPA, passed in 2000, was designed to block access to images defined as "obscene," "child pornography," or "harmful to minors." Under CIPA, public libraries and schools receiving federal funding were required to install software filters on Internet-accessible computers. The Supreme Court held up the constitutionality of the law in 2003.

In 2014, the Internet is used drastically differently from how it was in 2003. CIPA doesn't account for social networks, collaborative websites, and content-driven sites that make up the web today. According to the ALA, sites such as YouTube, Google Drive, Facebook, and National Geographic may be filtered under the Children's Internet Protection Act. It's an out-of-touch, dated law that does more of a disservice to children than actually protect them.

Clunky Filters

According to Houghton, filters have about a 70-80% accuracy rate when it comes to blocking text. With multimedia, such as photos are videos, accuracy rate is even lower. Simply put, Internet filtering software cannot keep up with advancing technology.

Houghton referred to filtering software as "black boxes" due to their lack of transparency.  We don't know how most filters work because the companies that make them don't give a complete list of what they're blocking. They also don't disclose what kind of algorithm or formula they use to block certain words or images.

Houghton has spent hours attempting to crack filters. One example she gave was a filter that would block anything with the word "gay" in it, but allowed content with the word "lesbian." Basically, Internet filters aren't exactly smart about picking and choosing what and what not to censor. With such a mysterious (and faulty) filtering algorithm, how can libraries put their trust into such software?

The ALA's Office for Information Technology Policy (OITP) and the Office for Intellectual Freedom (OIF) did conducted extensive research on the impact of CIPA and Internet filtering on public libraries and schools. The study found that CIPA is often misinterpreted by organizations leading to overfiltering of the Internet. The result? Legitimate, educational resources were blocked while images deemed "obscene" or "harmful" were allowed. Talk about inaccurate.

Impact on Digital Inclusion

"When you put filters on children's computers, you do not have equitable access," said Houghton during the presentation.

Beyond blocking certain educational websites, filtering can also cause other patron needs to go unmet. According to the ALA, studies have found that filters can block out  resources dealing with topics such as war and genocide, safer sex, and public health. One study found that a filter blocked a website required for an online nursing exam!

Filtering out social networks or collaborative websites might result in a missed opportunity for students to learn digital literacy and career skills. Social networks are a large part of the modern workforce and a natural part of the way people communicate. Restricting access to them essentially denies that they exist – and that is a huge disservice to young people.

eople in low income communities or without broadband access at home use the library to find jobs, build skills, and gain access to vital information. Those who rely on public access computers for Internet access are disproportionally affected by filtering policies. 

Online Safety Education Matters

“One good education class is worth a dozen filters,” said Caldwell-Stone during the presentation.

This was thrilling to hear as TechSoup for Libraries just wrapped up a webinar on Training the Public on Internet Use. When patrons are educated on safely using the Internet, they are empowered to make better choices about the content and multimedia they use.

More Resources on CIPA and Libraries


Unfortunatly some institutions don't have a choice. The city council, school district administration or some other governing body has made the decision.

In this case, make the best of a bad situation by having control of the filtering at a local level. In other words, don't purchase one of the off-the-sheld products. "DansGuardian is designed to be completely flexible and allows you to tailor the filtering to your exact needs. It can be as draconian or as unobstructive as you want. The default settings are geared towards what a primary school might want but DansGuardian puts you in control of what you want to block." It's open-source.

A proxy server, like Squid, can also be used locally and configured to meet local requirements. It can also be used to block some advertisements which are served from third party sites. (A filtering I feel OK with)

Look around at what is available, keep decisions local.

BTW DansGuardian mentions it uses PICS. Is anyone still using that metadata? I remember that from 15 years ago maybe. Haven't heard of it in years, maybe a decade.

Hi David,

Thank you so much for your thoughtful comment and advice. It's true that many libraries don't have a choice in the filtering matter. I really like your advice to "keep decisions local."