Filtering has been a hot topic in the public library community since web access first became a service provided to patrons. Those in favour of filters claim that they are an effective security measure that keeps out unwanted content and does not impact on users in any detrimental way. Those opposed to filters cite instances when legitimate research material has been blocked by filters and argue that it is an excessive measure that harms more than it helps. Others take the middle ground and contend that although filters are problematic, they are the only realistic method of ensuring that public libraries remain as safe environments.

The debate has recently boiled over in the U.S. with the enactment of the federal Children's Internet Protection Act. This legislation, in part, places a requirement on public libraries to implement content filters on their internet access terminals in exchange for certain federal funding. In response, the American Library Association initiated a legal battle to have this requirement struck down. In the summer of 2003, the U.S. Supreme Court ruled that the filtering for funding requirement was constitutional and would stand. The ruling has left the American library community deeply divided. On one side are library boards that have voted in favour of installing filters on all library terminals. On the other side are boards against any filtering. In the middle are boards that have decided to compromise and have filters installed on some, but not all, library terminals (usually on terminals in areas reserved for children).

Although the Canadian scene has been less adversarial, a recent controversy at the Ottawa Public Library erupted in 2003 over the filtering issue. Some Ottawa library staff members filed a grievance through Canadian Union of Public Employees (CUPE) asserting that their board's no-filter internet use policy would result in staff being exposed to pornography in the workplace. A similar 'hostile environment' grievance was filed months earlier by some staff members of the Minneapolis Public Library. After heated debate in the spring of 2003, the Ottawa Library Board approved a motion to place filtering software on all terminals with the option given to adult patrons (16 years and older) to turn the filter off.

What are filters?

An internet content filter is a piece of software that, once installed on a computer, acts as a censor while you surf the web. Websites that are deemed offensive according to the criteria incorporated into the software program will be blocked so that you will not be able to view them with your web browser. Filters are currently installed on computers in public and school libraries, in workplaces and in many other settings. Some parents opt to install this software on their home computers in order to have better control of their children's internet use.

How do internet content filters work?

There are a variety of different types of filtering programs. Some filters verify the requested URL against a list of permitted and prohibited addresses. Other filters will assess the content on a site dynamically and will block access to content that includes certain characteristics (e.g., stop words such as "porn"; links to inappropriate sites; the presence of image files). While some products incorporate human assessors at some stage, other programs either evaluate sites on-the-fly or block sites based on a predetermined stop list.

Filters commonly block at the domain name level. This is problematic since this practice has a greater chance of resulting in over-blocking (i.e., blocking access to content that is actually appropriate according to the criteria used in the filtering process).

Critics consider filters to be crude instruments that cannot adequately assess the appropriateness of web content. Some well known examples of web content that is often blocked, yet should not be, include articles about Superbowl XXX and websites dedicated to breast cancer and sexually transmitted diseases. Also, filters occasionally fail to block material that is inappropriate and illegal.

Another critical shortcoming of filters is the problem of prior restraint (i.e., ideas are censored out before they ever reach the internet surfer). A person using filtered access at a public library in Canada may not know what content was blocked. Unless that user has the permission to turnoff the filter, at best they'll be presented with a message that alerts them to the fact that some content was blocked.

What criteria is used to distinguish between sites that ought and ought not to be blocked? Who determines this criteria?

The developers of filtering programs determine the criteria and methods used in distinguishing between an appropriate and inappropriate site. Since the business of designing filtering programs is competitive, these methods are treated as trade secrets by the developers. Therefore, it can be very difficult to ascertain whether a certain filter will over-block until it is installed and used; it is only at that point that a librarian would be informed, for example, that a given web content provider is a victim of over-blocking.

Also, it is possible for an end user, such as a library, to adopt a rating scheme. These schemes when installed in conjunction with a filter or browser enables web searching that is tailored to certain content preferences. Rating schemes may be created by the software developers or by a third party. The end user indicates their desired level of exposure to a certain category of content on a scale (e.g., violence scale of 3) and the filter or browser identifies content that meets the desired criteria by either referring to a compiled list of sites matching the end user's rating selection or by reading the labels that participating content providers have applied to their websites.

The Platform for Internet Content Selection (PICS) is a protocol that has been adopted to facilitate the use of rating schemes. It is a standard that enables users to block or unblock web content that is labeled. In order for a PICS compliant rating scheme to function, the user's browser or filter and the content holder's labels must both be PICS compliant.

According to a survey conducted by Ann Curry and Ken Haycock of the School of Library1, Archival and Information Studies at the University of British Columbia in April 2000, of the public and school libraries in the survey that filter, 21% "...use systems that allow access only to a defined universe of approved sites supplied by the vendor.... [and approximately 12%] limit their users to a list of sites approved by the library".

The control exercised by software developers over filtering criteria is alarming. According to the survey by Curry and Haycock 55% of the public libraries in the survey that use filters use "vendor-supplied words or phrases for keyword blocking"; 15% complement the vendor-supplied lists by adding selected words and phrases. Alternatively, 56% of public libraries in the survey that use site-blocking filters "...use vendor compiled lists of Web sites2." However, Curry and Haycock reported that "[a] majority of librarians (54%) who use filters don't know whether they have access to the list of blocked sites.

Another distressing discovery from the Curry and Haycock survey is that a significant number of public librarians do not fully understand how filters work or how criteria for identifying a blocked site is developed: "19 percent lacked information about their keyword blocking, 27 percent about site blocking and 60 percent about Web rating systems." Curry and Haycock suggest that some public librarians were not sure "...which type of blocking their filter employed3."

Is there any way to get around a filter?

Canadian public libraries prohibit circumventing the filter. For instance, the Calgary Public Library policy states: "Anyone who...attempts to subvert any security devices that the Library has installed, will have their library privileges revoked and may be reported to the police."

How can I find out whether a particular filtering program is blocking my internet site? What can I do if a particular filtering program blocks my site?

You could download a trial version of the software, if available, or contact the software developer or distributor directly. Since the stop lists or the algorithms used by these software developers is proprietary information, they'll likely not give you access to this information. However, they may let you know if your content is blocked. It is possible that by doing this you could persuade the distributor to adjust their product to ensure that your content is not blocked. If blocking your content would embarrass the vendor in the media by illustrating how the vendor's product over-blocks, then there is a greater likelihood that the vendor will cooperate and arrange to have your content unblocked.

In terms of the brands of filtering software that Canadian public libraries use, Curry and Haycock reported that

"Cyberpatrol software dominated the public library segment, with 43 percent of the market. Surfwatch (8 percent) and Websense software (6 percent) were distant runners-up. Other software mentioned by public library respondents were made by Screendoor, Border Manager, Foolproof, SmartFilter, Searchopolis, Net Nanny, Winu, Guard, Airswitch, and Library Guardian.4"

Alternatively, you could complain to your city Alderman, your Member of Provincial Parliament or contact the media.

Are filters effective at blocking access to child pornography and other illegal content on the internet?

A common complaint about filters is that they are not 100% effective in blocking out inappropriate material. Generally, Canadian public libraries warn patrons that filters are not perfect and that parents should monitor their children's internet use, even on filtered terminals.

Do Canadian public libraries use internet content filters?

Use of filters in Canadian public libraries varies considerably. Some libraries have no filters installed on any internet access terminals. Others have filters installed on some terminals, usually on the computers in areas reserved for children. Still others have filters installed on all terminals available to the public. Of the libraries with filters on all terminals some provide adult patrons with the option to surf with the filter turned off. According to Curry and Haycock's survey conducted in April 2000, 21% of public libraries use filtering software and only 5% of public libraries use filters on all terminals and, at the time of the survey, 69% of public libraries had no plans of installing filters.5

Many of the libraries that do have at least some filtering note that such measures are comparable to the acquisition choices made in maintaining their print collections. The Vancouver Public Library, for example, notes in its policy: "This policy is consistent with our book and materials collection policy which stresses children's collections be appropriate for age and interests of children."

While some Canadian public libraries guarantee that they will respect the privacy of internet users, others state openly that they may monitor patron use of the internet. The Fraser Valley Regional Library notes:

"The Library will make reasonable efforts to protect the privacy of every user, but this privilege cannot be guaranteed. The Library reserves the right to review or suspend Internet usage as follows: As required by law; As part of system maintenance activities; If improper or illegal use is suspected."

Alternatively, the Vancouver Island Regional Library states in its policy that "Staff do not monitor Internet use." In some libraries, patron use of the internet is tracked by library card while in others, no card is required to gain access.

How will I know whether my internet access is being restricted (or filtered) at my local public library?

Check the library's policy. Although some Canadian public libraries (surprisingly) do not have policy statements on internet use, most do. If it is not clear in the policy whether filtering tools are used, contact the your library directly. Since filters often operate in the background, you may be unaware that the terminal you are using has a filter on it. Look for signs posted around the library that alert patrons to the fact that certain machines are filtered. In libraries that have installed filtering software on some or all of their machines, ask a librarian for non-filtered access.

How will I know whether my kids are using filtered or non-filtered access at the local public library?

The starting point should be the library's policy. Generally, Canadian public libraries place the onus of monitoring the use of internet from library terminals on parents and guardians, regardless of whether the library has opted to install filters. However, there is also considerable variation in policies in terms of the age used to differentiate between those who can and cannot use unfiltered access without parental permission. Some libraries have no age requirement for gaining unfiltered access to the internet. Other libraries require that a child must be accompanied by an adult in order to be permitted to use an unfiltered terminal. Some libraries permit children of a certain age to gain unfiltered access while unsupervised so long as they have obtained written permission from their parent or guardian in the form of a signed library permission slip. The precise age used by the different public libraries in determining when a young patron is able to use unfiltered access, either with parental permission or without, varies widely (from 10-18 years of age). Where parental permission is required, a parent may be required to sign the form in the presence of a library staff member.

If a filter at my local public library prevents me from accessing a particular internet site on a library terminal what can I do to about it?

If your library has installed filters on some of their computers you may need to ask a librarian to provide you with unfiltered access. Depending on the library's policy, this could be achieved by moving to a different terminal or by turning the filter off on the machine you're using. Unless the information you are seeking violates the library's acceptable use policy you should have no problem requesting that the site be unblocked. The danger, though, with filters is that there may be content available on a subject that you are investigating that you'll never realize you've missed since these programs block content before you have an opportunity to decide for yourself whether the material is relevant to your research.

Take note that in some libraries, filters are installed on all terminals and patrons are provided with unfiltered access only upon request.

If a public library is blocking access to my internet site what can I do to get the library to change its position?

Libraries generally reserve the right to adjust their filtering programs or to make requests for changes directly from the software provider. First, inform the library of the fact that your content is blocked. Check their internet use policy to determine whether your content would be deemed appropriate or not. The library may be unaware that your site is blocked and a simple, polite request may be sufficient to have your content unblocked. If the library refuses you may need to raise the issue at a meeting of the library's board. Alternatively, you could complain to your city Alderman, your Member of Provincial Parliament or contact the media.

If I disagree with filtering in public libraries what can I do to about it?

If you disagree with the use of filters at your local library you may raise the issue at the next meeting of the library's board or complain to the library committee responsible for the policy. The Vancouver Island Regional Library, for instance, notes in its policy: "The Library welcomes customer, staff and public feedback on its Internet Policy. The Executive Committee reviews the Internet policy annually at its second meeting of the year."

Alternatively, you could complain to your city Alderman, your Member of Provincial Parliament or contact the media.

Endnotes

1 Ann Curry & Ken Haycock, "Filtered or Unfiltered?" (2001) 47:1 School Library Journal 47.
2 Ibid. at 45-47.
3 Ibid. at 45.
4 Ibid. at 45.
5 Ibid. at 45.

Resources

Cases

United States et al. v. American Library Association, Inc., et al. 123 S.Ct. 2297

The U.S. Supreme Court held that the Children's Internet Protection Act (CIPA), which, in part, places an onus on public libraries to install filters in order to be eligible for certain Federal funding, did not violate the constitution. This decision overturned a Federal District Court ruling that the provisions related to public libraries were unconstitutional.

American Library Association, Inc., et al. v. United States, et al. Multnomah County Public Library, et al. v. United States of America, et al. 201 F. Supp. 2d 401

In this U.S. Federal District Court decision the American Library Association was challenging the constitutional validity of the Children's Internet Protection Act (CIPA). The CIPA placed an onus on public libraries to install filters in order to be eligible for certain Federal funding. Although the decision was recently overturned by the U.S. Supreme Court, the ruling still provides an excellent overview of the U.S. case law and legislation surrounding censorship and the filtering debate including the arguments for and against filtering and the inadequacies of filters.

Filtering in the London Public Library

In 2007 and 2008, the London Public Library was considering an expansive plan to install filtering across the majority of public access terminals using a proprietary filtering solution. CIPPIC intervened with a letter to the Board to express concerns that the Board had not reached a conclusion that properly accommodated freedom of expression.

Articles

The Ottawa Public Library Filtering Debate (2003)

Even librarians, many of whom pride themselves on representing a profession that abhors censorship, are doing some soul searching over the issue of content filters. Wendy Adamson's account of what went on at the Minneapolis Public Library and why several members of the library staff decided to bring a harassment suit against their employer is enough to shake the confidence of any civil libertarian. As Adamson herself noted: "What were the images like? Warning - this may offend some readers."

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This page last updated: June 2, 2007

By Robert Dupelle

FAQs

Resources

Cases

United States et al. v. American Library Association, Inc., et al. 123 S.Ct. 2297

The U.S. Supreme Court held that the Children's Internet Protection Act (CIPA), which, in part, places an onus on public libraries to install filters in order to be eligible for certain Federal funding, did not violate the constitution. This decision overturned a Federal District Court ruling that the provisions related to public libraries were unconstitutional.

American Library Association, Inc., et al. v. United States, et al. Multnomah County Public Library, et al. v. United States of America, et al. 201 F. Supp. 2d 401

In this U.S. Federal District Court decision the American Library Association was challenging the constitutional validity of the Children's Internet Protection Act (CIPA). The CIPA placed an onus on public libraries to install filters in order to be eligible for certain Federal funding. Although the decision was recently overturned by the U.S. Supreme Court, the ruling still provides an excellent overview of the U.S. case law and legislation surrounding censorship and the filtering debate including the arguments for and against filtering and the inadequacies of filters.

Filtering in the London Public Library

In 2007 and 2008, the London Public Library was considering an expansive plan to install filtering across the majority of public access terminals using a proprietary filtering solution. CIPPIC intervened with a letter to the Board to express concerns that the Board had not reached a conclusion that properly accommodated freedom of expression.

Articles

The Ottawa Public Library Filtering Debate (2003)

Even librarians, many of whom pride themselves on representing a profession that abhors censorship, are doing some soul searching over the issue of content filters. Wendy Adamson's account of what went on at the Minneapolis Public Library and why several members of the library staff decided to bring a harassment suit against their employer is enough to shake the confidence of any civil libertarian. As Adamson herself noted: "What were the images like? Warning - this may offend some readers."

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