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tshirtA Washington State Supreme Court decided yesterday in a 6-3 decision that public library internet filtering is not censorship, because filtering is “collection development.”  You can read more in Library Journal, on ReadWriteWeb, or read the actual court decision and the majority and dissenting opinions.

My reaction is simple, as someone who has fought, and won, an internet filtering challenge in my own library. Our communities’ intellectual freedom is at risk.  This is a huge step backward for intellectual freedom.  And if we follow the logic in this case, the Library is leaving their internet collection development up to an automated software system and some untrained minimum-wage lackeys at the filtering company.  Filters are not collection development and filters don’t work.  My frustration at the decision-makers’ lack of education about these issues is immeasurable.

I posted comments on the LJ & RWW sites.  Those comments are duplicated below.  If you want to know more about filters, read on.

This is a gigantic issue for public libraries and I have serious fear about what this means for our communities’ future of information access.

ReadWriteWeb’s coverage brought up the ethical argument against filtering. Just because someone is using a library computer, does that mean that he or she automatically has less access to information? It shouldn’t, and libraries are fighting for information access rights every day.

Besides the ethical argument against filtering there are plenty of practical arguments. Namely, filters don’t work, they cost a lot of money, and take a lot of time to operate.

I’m the Digital Futures Manager for the San Jose Public Library. A couple of years ago, a filtering challenge was brought by one of our city council members to the library. We were told to filter, we said no, and we embarked upon an extensive study about the effectiveness of filters, which you can find at: The overall results? Internet filtering software **does not work**.

Looking at our own library’s study as well as all of the published studies done in the last decade [**see the end of this post for a complete table**], it’s consistently found that 15-20% of the time, content is over-blocked (e.g. benign sites that are blocked incorrectly). And 15-20% of the time, content is under-blocked (e.g. sites deemed “bad” gets through anyway). We found that overall, filters have only about a 60-70% accuracy rate for traditional text content.  Looking at all surveys of filtering accuracy from 2001-2008 (no studies have been done in 2009 or 2010 that I’m aware of), the average accuracy of all the tests combined from 2001-2008 was 78.347%, and that is measuring only text content with only one study looking at images.  If we think “well, filters get better over time, right?” and only look at studies from 2007-2008, we see a nominally higher accuracy percentage: 83.316%.  So, while filters may be getting a little better…they’re still wrong 17% of the time for text content, and over half the time for image, video, and other non-text content.  If you think about what that means practically speaking for your browsing experience, you may think: “We’re spending money and time on these systems why again?”

Filters simply do not work on multimedia content, which is usually what people think the filters are for (naughty videos and photos). The accuracy in filtering images, audio, video, RSS feeds, and social networking content is embarrassingly low: about 40%. That means that *over half the time*, the filter makes the wrong decision about blocking a photo or video. Again, why would we foist these failed systems willingly upon our communities?

And how do filters work? There are automated little spiders crawling the web, looking for naughty content — usually there’s a formula (which the companies will never tell you) that looks for some combination of trigger keywords, trigger URLs, if there are too many images on the site, a weird combination of letters & numbers in the URL, etc. If the spider determines something fits in the “naughty” category, then there it goes. If the company is particularly vigilant (often not the case), they will have some minimum-wage untrained lackey spot-checking results from the spider. So if a filter constitutes collection development, we have left our online collection development in the hands of an automated software system and untrained non-library staff. Worse yet, the company won’t even tell us why or how they choose to categorize items. You usually do have the ability to add things to the white list (OK stuff) or black list (naughty stuff). But as subjectivity is key in issues of content, even among library staff, who gets to decide what is bad and what isn’t?

Also concerning is that library customers report usually not being willing to ask for something to be unblocked for them as they are embarrassed as the library has automatically put them in the position of looking at something “naughty” even if it isn’t. So how many of our library customers walk away without the information they need? And whose fault is that? Ours!

Beyond that, the time that it takes for staff to unblock sites and handle the administrative paperwork to do so is incredible — many libraries estimate it at 60 minutes of staff time per request. The return on investment of dollar and time investment is negative. You lose when you install a filter.

And that’s the bottom line. Filters make the library lose money and time. Filters make the customers lose access, time, and confidence in the library’s use and relevance.

People who want to install filters in libraries have the best intentions (usually). They think that it will “protect the children” or “filter out pictures of penises.” Sadly, the technology has not caught up with our expectations for how it should work. People truly believe that filters work, but only because they haven’t looked at the research or tried one out themselves. If there were filters that didn’t overblock or underblock, I’d be the first in line to take a look at them. But the software is fallible. And turning over an entire community’s freedom of information access to a known-failed software system is just about the most foolish thing any library could choose to do.


Filtering Studies and Their Findings, 2001=2008 (no studies found in 2009 or 2010)

Average accuracy 2001-2008: 78.347%
Average accuracy 2007-2008: 83.316%

(someone made an argument that if we only count recent survey results, the accuracy will be significantly higher, but it’s less than 5% higher, within the margin of error cited in all of these surveys)

Date Title Source Summarized Conclusions
2008 Protecting Children on the Net with Content Filtering EU Safer Internet
  • Average score from tests of 26 different filtering tools showed the following levels of accuracy in both blocking trigger websites and allowing non-trigger sites:
  • Testing content appropriate for kids 10 years or younger – 2.2/4.0 (55%)
  • Testing content appropriate for kids 10 years or younger (testing pornographic content only) – 2.8/4.0 (70%)
  • Testing content appropriate for kids 11-17 – 2.0/4.0 (50%)
  • Testing content appropriate for kids 11-17 (testing pornographic content only) – 2.8/4.0 (70%)
  • Study noted that “filtering solutions are not yet capable of accurately filtering typical Web 2.0 user generated content, such as video clips on YouTube or MySpace, and harmful scenes in Second Life” and “filtering on chat and IM is often inconsistent.”
2008 Closed Environment Testing of ISP-level Internet Content Filtering Australian Communications and Media Authority
  • 84%-95% accuracy blocking trigger websites
  • 92%-97% accuracy allowing non-trigger sites
  • The success of all products at blocking trigger websites was inversely proportional to their success at allowing non-trigger sites.
2008 Deep Throat Fight Club Open Testing of Porn Filters Untangle
  • Fortinet 97.7% accuracy blocking trigger websites
  • Watchguard 97.3% accuracy blocking trigger websites
  • Websense 97.0% accuracy blocking trigger websites
  • SonicWall 96.1% accuracy blocking trigger websites
  • Barracuda 94.0% accuracy blocking trigger websites
  • Average of 99% accuracy allowing non-trigger sites
2008 Expert Report Dr. Paul Resnick (for North Central Regional Library District)
  • 93.1% accuracy blocking trigger websites
  • 48% accuracy blocking trigger images
2007 Report on the Accuracy Rate of FortiGuard Bennet Haselton (for the ACLU)
  • 88.1% overall accuracy on .com sites
  • 76.4% overall accuracy on .org sites
2006 Expert Report Philip B. Stark (for the DOJ)
  • 87.2%-98.6% accuracy blocking “sexually explicit materials”
  • 67.2%-87.1% accuracy allowing “non-sexually explicit materials”
2006 Websense: Web Filtering Effectiveness Study Veritest (for Websense)
  • WebSense: 85% overall accuracy
  • SmartFilter: 68% overall accuracy
  • SurfControl: 74% overall accuracy
2004 Report on the evaluation of the final version of the NetProtect Product
  • Surf-mate: 85% accuracy blocking trigger content and 89% accuracy allowing non-trigger content
  • CyberPatrol: 44% accuracy blocking trigger content and 95% accuracy allowing non-trigger content
  • Net Nanny: 18% accuracy blocking trigger content and 97% accuracy allowing non-trigger content
  • CYBERsitter: 24% accuracy blocking trigger content and 97% accuracy allowing non-trigger content
  • Cyber Snoop: 3% accuracy blocking trigger content and 99% accuracy allowing non-trigger content
  • NetProtect 2: 96% accuracy blocking trigger content and 83% accuracy allowing non-trigger content
2003 Internet Blocking in Public Schools Online Policy Group
  • School curriculum materials accessed with filters set to least restrictive settings: 95-99.5% accuracy
  • School curriculum materials accessed with filters set to most restrictive settings: 30% accuracy
2002 Corporate Content Filtering Performance and Effectiveness Testing Websense Enterprise v4.3 eTesting Labs (for Websense)
  • SuperScout: 90% accuracy blocking “adult” materials
  • SmartFilter: 90% accuracy blocking “adult” materials
  • WebSense: 95% correct accuracy blocking “adult” materials
2002 No Evil: How Internet Filters Affect the Search for Health Information Kaiser Family Foundation
  • 98.6% accuracy in accessing health information on least restrictive settings
  • 95% accuracy in accessing health information on intermediate restrictive settings
  • 76% accuracy in accessing health information on most restrictive settings
2001 Expert report of Dr. Joseph Janes Dr. Joseph Janes (for the ACLU)
  • 34.3% accuracy in allowing non-trigger content
2001 Internet Filtering Accuracy Review Cory Finnell for the Certus Consulting Group (for the DOJ)
  • CyberPatrol: 92.01%-95.31% overall accuracy
  • Websense: 89.97%-94.75% overall accuracy
  • Bess: 93.08%-91.64% overall accuracy
2001 Updated Web Content Software Filtering Comparison Study eTesting Labs (for the DOJ)
  • 92% average accuracy of four filters in blocking “objectionable” content
  • 96% average accuracy of four filters in allowing non-trigger content
2001 Digital Chaperones for Kids Consumer Reports
  • Cybersitter 2000: 78% accuracy blocking “objectionable” content
  • Internet Guard Dog: 70% accuracy blocking “objectionable” content
  • AOL’s Young Teen Control: 63% accuracy blocking “objectionable” content
  • CyberPatrol: 77% accuracy blocking “objectionable” content
  • NetNanny: 48% accuracy blocking “objectionable” content
  • NIS Family Edition: 80% accuracy blocking “objectionable” content
2001 Effectiveness of Internet Filtering Software Products Paul Greenfield, Peter Rickwood, and Huu Cuong Tran (for the AustralianBroadcasting Authority)
  • N2H2 (now Bess), set to “maximum filtering,” was reported as the most effective  filter tested in this study
  • 95% accuracy blocking the “pornography/erotica” category
  • 75% accuracy blocking the “bomb-making/terrorism” category
  • 65% accuracy blocking the “racist/supremacist/Nazi/hate” category
  • 40% accuracy allowing non-trigger content in the “art/photography” category
  • 60% accuracy allowing non-trigger content in the “sex education” category
  • 70% accuracy allowing non-trigger content in the “atheism/
  • anti-church” category
  • 80% accuracy allowing non-trigger content in the “gay rights/politics” category
  • 85% accuracy allowing non-trigger content in the “drug education” category
2001 Report for the EuropeanCommission: Review of Currently Available COTS Filtering Tools Sylvie Brunessaux et al.
  • Average of the 10 filters tested
  • 67% accuracy blocking trigger sites in English
  • 52% accuracy blocking trigger sites in five languages
  • 91% accuracy allowing non-trigger content

“Why internet filters don’t work and why libraries who filter are wrong”

  1. Phil Bradley Says:

    Surely collection ‘development’ implies growth, larger, increasing and so on, while filtering is the exact opposite – reduction of data, opportunities and so on. Madness!

  2. walt crawford Says:

    One really annoying thing: CIPA is only supposed to deal with visual content. And, you know, based on the actual Supreme Court’s decision, all it should really take to disable filtering is two checkmarks: 1. I am over 18 years old. 2. I want filtering turned off for this session. Unfortunately, the law has been overapplied, and this first as-applied test is going the wrong way.

  3. Tweets that mention Why internet filters don’t work and why libraries who filter are wrong: A Washington State Supreme Court decided y... -- Says:

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  4. David James Says:

    The ultimate question however is, how much “legitimate” content is wrongly filtered compared to how much “bad” content would then be available if there were no filtering software in place. At my library, I know it would be a nightmare – the porn would be flowing freely everywhere you look. On the flip side, the number of legit sites that have been blocked (by our software at least) and reported by patrons… well I could probably count them on two hands over the past 10 years. Of course no filtering software is perfect – you are never going to be able to do anything about data that is transmitted via email obviously – but by and large I’d say the positives of filtering far outweigh the “censorship” end of the argument. Free and public information is wonderful – free and public porn, not so much.

    I’d also be remised if I didn’t mention I was a bit miffed at the repeated shots at the “minimum-wage lackeys at the filtering company.” I’m not sure how to take this – because they aren’t highly paid or educated (presumably), they must be bad at their jobs? They aren’t MLS toting librarians, so they couldn’t possibly know what is best for the public at large?

  5. Ian McKinney Says:

    I think whether to use filters or not is a complex issue that must balance collection development policy, intellectual freedom policy, the law, staff safety, research about how particular filters work and what they cost, and common sense. I think libraries that exercise due diligence in these areas will still reach different conclusions about whether to filter, and I can’t see that as a bad thing.

    @Phil B.: Collection ‘development’ also implies selection. With millions of web sites, billions of photos and videos, and global digital output expected to surpass 1.2 zettabytes sometime this year, how many staff do you have to have to make sure it all meets your library’s collection development policy? It’s fairly obvious to me that seeing the internet as part of your collection or as needing to meet a collection development policy standard is the wrong model. You either have the internet, or you have it and filter some of it, or you don’t have it. And even if you have filters, your internet ‘collection’ still grows at an incredible rate. Of course, so does the part of the internet you filter, purposely or not, and that is a problem – but to me, if you’re going to filter, you need to manage the process and be diligent about what’s getting filtered.

    My library does use a filter (Websense, which works very well with multimedia content, as well as with working with our requests to add or subtract sites both for their lists and for ours) and most of our staff are pretty satisfied with both A. the operation of the filter and B. where that leaves us philosophically. What it sounds like Sarah is doing with this article is quoting statistics and data that are an aggregate – not all filters are created equal. Not all libraries are reasonable about what happens when a request to remove the filter comes in. It’s nothing like 60 minutes at my library. It’s probably nothing like 5 minutes.

    This data is also apparently aggregated over the last ten years. I think it’s probably reasonable to suggest that filters from 2001 were much worse at doing their job than filters from 2010 – but I could be wrong, it could be the other way around. *Either* way, data from the last ONE year would impress me a lot more.

  6. Sarah Says:

    @ David James: The fact that so few of your customers reported over-blocked content proves my point. The filters have been tested over and over again, and show 15-20% overblocking. If only a couple asked library staff to unblock anything, that proves to me that they just walked away without access to the content they should have had access to in the first place without going through the rigmarole of asking staff for help. Additionally, the minimum-wage lackey reference has nothing to do with these filtering company workers not having MLSs. Come on. It has to do with them being untrained, and literally the library is leaving what is and is not blocked in the hands of someone who hasn’t been trained, isn’t well-paid for doing the work they’re doing, and hasn’t received any guidance from the library on what is and is not acceptable content. If the person has a prejudice against people of color–guess what? Sites advocating for minority rights might end up in the blocked pile. And if the company is pro-life and instructs its employees to block pro-choice sites, guess what happens? My point is that no single person, much less an untrained poorly-paid person low on the totem pole in a filtering company, should ever have control over what our customers are “allowed” to look at.

    @ Ian McKinney: You raise a good question about data over the last ten years perhaps being weighted toward filters that didn’t work 7 or 8 years ago. But the interesting thing is that even if you limit your sample to studies done in the last two years, or four years, the statistics end up the exact same. Filters aren’t getting better overall, and they sure as crap aren’t getting better at blocking the content everyone thinks they filter so well: photos and video. I’m glad to hear that unblocking isn’t a huge workload at your library, and that you feel your filter works well. So here’s my challenge to you. I challenge you to create a study of common web needs of a customer, and go in to see what gets over-blocked. Then go in purposely looking at sexually-explicit materials in various formats, and see how well the filters do with that. My guess is that if you’ve spent a lot of time customizing your white list and black list, your filter might perform slightly better than the average, but dollars to doughnuts the overall accuracy percentage would still be fairly low.

    My point is this: The software doesn’t work well. Why are we using it? It creates a false sense of security that in effect, more often than not, over-blocks or under-blocks instead of doing its job correctly. Why put that barrier in place for our customers? Why spend money and time on a piece of junky software that doesn’t work?

  7. Why internet filters don't work and why libraries who filter are … | Free Job Search Info Says:

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  8. Mel Says:

    I have to agree with David James. As a front line librarian at a busy public library branch who is on the ref desk for the majority of the day, I can say with certainty that the only reason we don’t have a problem with porn on public computers is because of the filtering software. Frankly, dealing with griping about computer wait times, patrons who don’t know what they’re doing online, telling people to turn down the volume, etc. all day does not make me relish the idea of becoming a human censor because the computers don’t automatically filter out porn. I didn’t get an MLS in order to run a computer lab, but sadly that is what a large part of my job has become. Filtering software isn’t perfect, but from where I’m sitting it is (a lot) better than nothing.

  9. JJR Says:

    It’s sad that Filtering is the default solution when a low-tech (but more costly) work around is available, like sunken privacy screens viewable only to the user, and perhaps screens which logout after 30 seconds idle time, to deter those sick pervs who want to force others to look at pr0n by pulling it up then walking away from the computer intentionally. But specially situated screens like that cost money, while many library directors would rather spend less money on filtering software of one kind or other.

    Completely unrelated, but I do appreciate that my local public library has a couple of “Catalog Only” machines….I’ve been in libraries that don’t have this arrangement, and I hate it when I want to look something up in the catalog but ALL of the terminals are in use by kids playing games, people paying bills online, etc. One time I realized it would probably be faster for me to drive home and access the catalog from home than it would be to sit around and wait for a terminal to be free.,,days like that make me long for a card catalog or an old, unsexy amber-screen NOTIS system display.

  10. Chris Says:

    Read the Library Journal article. It has a comment by you than a comment by someone who quotes a case saying the ACLU now says filters work. 95%? What’s going on?

  11. Shelley Says:

    I have no strong feelings on this issue, and what you say makes sense, but I know my college was concerned about people feeding their gambling addiction by using college computers to go on gambling sites….

  12. Vrije internettoegang: vervolg « Meeting Point Mediawijsheid Says:

    [...] Posted on 10/05/2010 by bieberwin In een artikel van Sarah Houghton-Jan die in haar blog Librarian in Black een soortgelijke discussie bespreekt over internetfilters die in Nederland ook wordt gevoerd. Er is [...]

  13. Winston Smith Says:

    Ignorance is Strength. “Collection development” my ass.

  14. ahniwa Says:

    A couple other things to consider (about the NCRL case in particular):

    There are 28 libraries in the NCRL system; 14 of them serve as the de facto school libraries for their school districts. 16 of them only have one computer in the building. Most of them are very small libraries, in very small communities (the largest about 2000 sq ft).

    These libraries are essential to these small communities where people can’t afford broadband and where kids need a quiet place to study.

    This case determined that libraries have the right to filter, not that they have to filter, and I think that any decision that gives more choice and local control to libraries is a good thing.

    Consider: half of these libraries are school libraries; no one in their right mind would ever say that people should be able to surf porn on a school library computer …

  15. Sarah Says:

    @ahniwa: Local control is good for most things, unless the issue in question has to do with fundamental human rights, which in this case it does. Access to information is a right, not a privilege. I am not in favor of local control, of giving anyone the ability to filter, ever. Filtering is immoral and unethical, and to me it’s the lazy and uneducated way out. Pinning all of your children’s information access on a faulty computer program and giving them & their parents a false sense of security & protection is not an acceptable act for any library. I realize not everyone agrees with that, but based on the empirical evidence in front of us I have a hard time understanding why anyone would disagree. No one is saying kids should be able to surf porn on a school library computer. What I am saying is that because these filters DO NOT WORK AS ADVERTISED, & I have the stats to back it up from dozens of studies, these same kids will be blocked from numerous legitimate sites that are incorrectly blocked (about 15-20% of the time) and even worse, 17% of that “porn” will get through anyway. That’s the problem. They don’t work.

  16. ahniwa Says:

    Yes, filters pretty much suck. Filtering is not a great solution. The ideal solution would be to have a bunch of computers located and screened and monitored in such a way that library staff may allow adults to look at porn in one area without a very high risk of some passing kid suffering some visual trauma.

    But we can’t all afford the ideal solution, so we do what we can. Filters may not be perfect, or even good, but I don’t think they’re hellspawn, either, and they can serve a purpose, especially in these tiny, poorly staffed libraries.

    (on a sidenote, would you remove my email address from your comment above? I’m afraid of spambots. thanks)

  17. Sarah Says:

    We are just going to have to disagree then. I think filters are hellspawn, as I think anything that limits freedom of information is hellspawn.

    I also question the assumption that sex & naked body parts traumatizes young people. It’s fine if they see a bloody war movie with severed arms and heads flying everywhere and intentional cruelty, but show then a piece of the naked body and everyone freaks the heck out. Again, I realize not everyone feels that way, but that supports my point. No one person, group, or corporation should ever act in loco parentis for anyone — kids or adults. It’s up to you to govern your own behavior, up to you to decide what’s best for your kids–but no one gets to tell me what my kids can’t look at. That’s not up to you.

    (& your email was removed — sorry)

  18. ⌘f | stop talking about internet filtering Says:

    [...] is nothing good about internet filtering on library computers, let me get out of the way. Sarah Houghton-Jan did a piece on this topic late last week and she says it well with a ton of data and invective to [...]

  19. Sarah Houghton-Jan (Librarian in Black) Says:

    OK Dan, now you’re just being silly.

    What information have i “failed to disclose”? What information do I have that is old? What newer information do you have that trumps everything I have here? I have literally got every study done about this in the last decade, have tracked court cases, filtering challenges in libraries nationwide, and follow developing laws that affect the issue. What have I failed to list here? What information have I not included? If there are studies I”m missing, or new developments in the technology or the law, I want to know about them. List them here. We’ll all take a look happily.

    You posted a private email you had with one librarian in one place, with no facts but only opinion from an individual. What does that prove? Please, do tell.

    The fact that filters don’t work is not “propaganda.” It’s a fact. I’m citing statistics comprehensively and describing how the technology actually works. You post incorrect information, misinterpret numbers without thinking it through, and post invective to appeal to people’s base instincts to “protect the children.” That’s propaganda.

  20. Andy Woodworth Says:

    Dan, if you are going to learn anything about librarians, it’s that we cite sources wherever possible. If you had stated in your original post of the listserv message at to where it was found (aka provide context), then it wouldn’t look like a private email from a random source answering an unknown question.

    And, as a science guy, one email or list serving does not prove anything. If you can cite multiple sources, then I would find that more convincing and compelling for a case that ‘filters work’. You can say that Sarah has failed to disclose ‘many many examples’, but without evidence or supporting documentation, it’s just a unsupported accusation. Sarah has provided a basis of support to her contention that filters do not work via posted links, so where’s yours?

    And, by the way, personal attacks detract from any statements of fact. My takeaway from your latest reply is that you like calling people names and making unsupported accusations, not that you have the facts on your side.

  21. J. B. Post Says:

    Though now retired, for years I have been suggesting the test of running the authors Lovecraft and Lovejoy through a search, both filtered and unfiltered to see just how much porn is kept out and how much real information is caught up in the filtering. I know of no one who has tried this. A small test, but it would at least give us some idea of what is gained and what is lost in a very small search.

  22. Information Access « Information Fluency Says:

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  23. Top Ten Links Week 19 | Librarian by Day Says:

    [...] New long post/rant on LiB: “Why internet filters don’t work and why libraries who filter are wrong“:  via @TheLiB – Sarah might call this a rant but it has more facts and statistics [...]

  24. Jim Wallace is just plain wrong « Welcome to my Says:

    [...] be clear FILTERS DON”T WORK. They only ‘Hide’ problems they don’t remove them, and the content the government [...]

  25. Jonathan Says:

    There’s a problem with your logic–and with your case studies. First of all, you have sampled only four of the hundreds of filtering services–only two of each kind (and not necessarily the best of them). When considering the question of whether filters can and do work, wouldn’t it be most logical to sample only the best models on the market? Either way, with such a small sampling, your margin of error is likely to be much higher than 5%.

    Second, even if the four services you selected represent a fair sampling of the entire filtering market, why would you average their failures together, unless it is to intentionally lower the overall appearance of their performance? If I was shopping for a home security system, I wouldn’t care what the average of the best and the worst models on the market was. If, say, the cheapest home security model only prevents break-ins 48% of the time, while the best model prevents it 99% of the time, I wouldn’t average them and conclude that any model of security system I buy will therefore only work 73% of the time. I would obviously choose the model that achieves the best performance. Neither would I conclude that since the best model might conceivably allow one thief in 100 to break in, that it is therefore not worth the investment.

    To say that filtering systems are at best 78% accurate, especially using an average of such a small sampling, is misleading in the extreme. Some of your case studies cite accuracy as high as 98% blocking for trigger sites and 99% for allowing for non-trigger sites. It seems obvious to me that the argument that filters “just don’t work” is fabricated (or at least, exaggerated) in order to give a fact-based facade to your opinion that filters are “hellspawn.” If you morally object to filters, fine. But saying that “filters don’t work” in order to justify your objections is dishonest.

  26. Internet Filtering Software is Not Collection Development | Information in Social Context Says:

    [...] Filters filter more than what we tell them to. The Librarian in Black lays out in her blog post, Why internet filters don’t work and why libraries who filter are wrong, all the various studies ab… comparing various studies of filtering.   Bennett Haselton’s Report on Accuracy Rate of [...]

  27. Aimee Says:

    I would like to review the report mentioned in your article, however the link is broken. Could you provide a new link?

    “… we embarked upon an extensive study about the effectiveness of filters, which you can find at: …”


  28. Sarah Says:

    The website changed. So you can find the documents now on this page: Take a look at the two documents listed under the June 11, 2008 meeting.

  29. Jon Says:

    Does anyone know any web-browser based filters (example: Add-ons for Mozilla Firefox/Google Chrome)?
    I have to do a presentation for one of my courses this semester, and I’ve decided to talk about censorship.
    I wanted to give them the experience of living in a world where the internet is censored.

    At first I was planning to use the China Channel add-on, but, unfortunately, it is not compatible with the Mozilla Firefox browser
    that is currently installed on the computers in our lecture hall.

    If you know any add-ons or plug-ins please let me know immediately!

  30. Tim Murtaugh Says:

    I was glad to find this. I’m SO frustrated by the filters on this very computer I’m using. They had one incident, ONE, and decided to go back to the filters. They’re insane! Okay I can understand maybe, filtering out XX rated material but gambling? All, or they think all of it is disallowed when the fact is, our govt. not only condones but encourages gambling….lotteries, casinos, etc. So how bad can that be?
    This isn’t the 1600s. Times change. I’ve had times were there was one word about gambling in the online Chicago newspaper and as a result, that was then made inaccessible. Another time, there was a short article about Playboy’s profits….no photos or X rated content. Yet the whole newspaper site was shut down.
    I’ve worked at a public library and talked about this with the head librarian. He agreed that filters don’t work and as long as he was in charge, they didn’t use them.

  31. Cameron Stone Says:

    The entire argument about library filters is based on one presumption….that porn is harmful. It isn’t. It isn’t immoral, illegal or unethical. If an individual does agree with or approve of adult material then don’t look at it. But it’s not the place of ANYONE to force personal beliefs on anyone else. Putting library computers behind a screen is NOT expensive and a one-time cost as opposed to the continual costs of filtering and new technology purchases.

  32. PORN IN THE LIBRARY! | Point of Contact Says:

    [...] The problem with filters is that they, at best, have a 60-70% success rate meaning 30-40% of the time the filter is actually blocking legitimate content or possibly letting questionable content through. The filters rely on proprietary algorithms through an expensive vendor that may or may not actually filter out the material the library wish to be filtered. These filters are also horrible at multimedia (images, video, feeds, Facebook, YouTube, Vimio, DeviantArt, whatever) so in order for them to work they need to blanket ban the entire site or a particular group of tags. Either way, legitimate material will get blocked while porn will still get through… [source] [...]

  33. CIPA, Censorship & the EFF | John the Librarian Says:

    […] Why internet filters don’t work and why libraries who filter are wrong by Sarah Houghton (posted on May 7, 2010) […]

  34. Ten Years of CIPA: Free Speech and Library Internet Filters | Comic Book Legal Defense Fund Says:

    […] studies published over the past decade and finding that on average, filters are only about 40% accurate at blocking multimedia. But for libraries in rural or impoverished areas, federal discounts and […]

  35. Filter This Says:

    […] software that libraries use to select what internet sites are viewable. And we’ll even assume, as the Librarian in Black insists ((Houghton-Jan, 2010)), that all filtering software available to libraries is pretty much […]

  36. Patrick Says:

    The solution to screens is simple. Have kid computers with the kids books. Have the Adult unfiltered computers surrounded by Adult Bookshelves, and have the screens pointed to the wall. No screens. Just rearrange.

  37. » It’s 404 Day! Join Us In Protesting Internet Censorship in US Schools and Libraries Says:

    […] Public Libraries, where one of our panelists today, librarian and blogger Sarah Houghton conducted a study of available filtering technology. It turns not that not only did filters allow for obscene images […]

  38. It's 404 Day! Join Us In Protesting Internet Censorship in US Schools and Libraries | americanpeacenik technology journal Says:

    […] Public Libraries, where one of our panelists today, librarian and blogger Sarah Houghton conducted a study of available filtering technology. It turns not that not only did filters allow for obscene images […]

  39. Today is 404 Day | Jennifer HLUSKO Says:

    […] Public Libraries, where one of our panelists today, librarian and blogger Sarah Houghton conducted a study of available filtering technology. It turns not that not only did filters allow for obscene images […]

  40. Libraries Against Filters | Jennifer HLUSKO Says:

    […] […]

  41. It's 404 Day! Join Us In Protesting Internet Censorship in US Schools and Libraries | Michigan Standard Says:

    […] Public Libraries, where one of our panelists today, librarian and blogger Sarah Houghton conducted a study of available filtering technology. It turns not that not only did filters allow for obscene images […]

  42. It’s 404 Day! Join Us In Protesting Internet Censorship in US Schools and Libraries « What's on my mind! Says:

    […] Public Libraries, where one of our panelists today, librarian and blogger Sarah Houghton conducted a study of available filtering technology. It turns not that not only did filters allow for obscene images […]

  43. Kendra Says:

    The advantage of web filtering is to block unwanted websites, Libraries are using it because some of students maybe opening porn sites (lol), but My question is what kind of web filter did you use? Because the filter I’m using is easy to handle and I can customized it on which site should be block.

  44. Sarah Says:

    Over the years I’ve tested a couple dozen filters. Expensive, cheap, complicated, simple. All of them block Constitutionally protected content, period. None of them works above about an 80% accuracy rating.

  45. ALA Report on Internet Filtering | John the Librarian Says:

    […] this report from the ALA is that it tells us the same things about internet filtering that the Librarian in Black has been telling us for years. It’s good to see her message recognized as an official stance of the […]

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